Ancient Roman religion
Other major deities
Ancient Roman religion encompasses the various religious beliefs and cult practices of ancient Rome. Romans offered cult to innumerable deities responsible for natural events and human affairs. Most of these cults were credited to Rome's divine ancestors and founders, her allies and her kings. Some Romans explained their personal success and high office as evidence of their own divine ancestry.
The priesthoods and cult to major deities and high offices of state were regarded as traditionally patrician preserves until opened to the plebians. Cult to Roman household deities was served by the paterfamilias and his familia (those under his protection). Some deities were served by women, others by freedmen and slaves.
Participation in traditional religious rituals was thought a practical and moral necessity for Romans of every class and occupation, and was embedded in personal, domestic and public life. Cult could be offered any deity or any combination of deities, as long as it did not offend mos maiorum (Roman tradition and custom). Rome's mystery cults were by their nature exclusive and secretive; little is known of them.
Some cult practices were explained or justified by Roman mythology; others remained obscure in origin and purpose. Cults and ritual provided sources for philosophical speculation, rather than doctrine or revelation. Even the most skeptical among Rome's upper castes acknowledged their necessity. Traditional religious practice was self-evidently the core of Rome's foundation, development and continued success. Religious novelty was a source of fascination and mistrust.
As Rome extended its influence and presence throughout the Mediterranean world, it encountered and absorbed further deities and practices by seeking (and often finding) their equivalence to its own or acknowledging their role in local identity and tradition. Some were officially embraced, some were tolerated. Others were condemned as alien hysteria, magic or superstition. Those that threatened traditional morality and unity were suppressed.
Under the Empire, numerous foreign cults grew popular, including the mystery cults of Isis and Eleusis, and deities of solar monism such as Mithras and Sol Invictus. Christianity eventually won support from Constantine I and in 391 it became the state religion under Theodosius I, to the exclusion of all other cults. Rome's traditional cults were condemned as "pagan", and were gradually transformed, absorbed or suppressed but retained their vitality through the 4th and 5th centuries. Rome's traditional religious hierarchy and many of its rituals remain ingrained in Christian ritual and many pre-Christian beliefs and practices survived in Christian festivals and local traditions.
Roman religio (pl. religiones) sought the alignment of earthly, human affairs (res humanae) with the divine (res divinae) through ritual. Rome's deities and divinities might respond favourably if correctly approached with an appropriate offering or sacrifice. In Roman religion, Orthopraxy (doing the right things) was more important than orthodoxy (believing the right things); right action was a cornerstone of Rome's mos maiorum (the customs and traditions "of the ancestors") and religio was a measured, rational activity which met the needs of the individual, the community and, insofar as their desires and requirements could be apprehended, the gods. Neglect of religio was a form of atheism, and imperiled the individual and the State. Excessive devotion and emotionalism in religio could be counterproductive, subversive or destructive, and was classed as superstitio.
Rites could be polluted by innovation, chance events or errors of procedure (vitium). Regardless of sincere intentions, polluted rites were at best ineffective; at worst, they might provoke divine anger and disaster. In the late 3rd century CE, Aelian applauded the pious "wisdom of barbarians" who practiced the "pure and unpolluted" rites of their ancestors.
Participation in public rites acknowledged a personal commitment to the community and its values: but particular rites could be polluted by those deemed impure under the relevant ritual law. In a ceremony of the Imperial era, a lictor commands the ritual expulsion of "the foreigner, the chained prisoner, the woman, the young girl!" On the other hand, only women could attend the secret rites of Bona Dea.
Without an appropriate and correctly delivered prayer, the gods could not know who was being addressed or what was being asked. Family meals and rites of passage were marked by vows, prayers and sacrifice to deities of household and family. The inconvenient delays of a journey, or the more fraught encounters of banditry, piracy and wreck might be averted by prayers for divine protection before setting out and an offering of gratitude on safe arrival. In times of great crisis, the senate could decree collective public worship, in which Rome's citizens – men, women and children – moved in procession from one temple to the next, to supplicate the gods for their help. 
Public prayers were offered loudly and clearly by a priest, on behalf of the community. Surviving liturgies tend to repetition and reiteration, as if to avoid any divine doubt of their intent. A similar declamatory, persuasive style was recommended for actors, petitioners and lawyers in court; the difference in priestly address lies its repetition, and its use of archaic and obscure language and gestures. Public religious ritual was enacted as a sacred drama whose true meaning might be apparent only to the gods.
Private prayers might have been produced in a more intimate, informal atmosphere, but surviving private liturgies are just as cautious and formulaic. Not all prayers and hymns were followed by sacrifice, but sacrifice without prayer was "thought to be useless and not a proper consultation of the gods". 
Roman commanders offered vows to be fulfilled after success in battle or siege; and further vows to expiate their failures. On one occasion, according to Livy, an enemy's protective deity was offered a deal; in a ceremony called an evocatio, Camillus promised Juno a temple in Rome as incentive for her desertion of Veii. He conquered in Juno's name, brought her cult to Rome and the city built her the promised temple. In the war against the Latins, Publius Decius Mus (consul 340 BC) vowed himself and the opposing army to the earth goddess and the shades of the dead (dii Manes) as an act of devotio in exchange for Roman victory: both sides kept the bargain. 
Deities bore witness to oaths of business, clientage and service, patronage and protection, state office, treaty and loyalty. As the refusal to swear lawful oaths, and the breaking of sworn oaths equally repudiated the fundamental bonds between the human and divine, both carried much the same penalty.
Sacrifice seems to have reinforced or revitalised the powers and attributes of divine beings, and inclined them to render benefits in return. Things offered or dedicated to the gods were sacer, and "blood offerings" were the most potent. The victims were domestic animals, typically cattle, sheep and pigs; each must be the best possible of its kind. They were cleansed, clad in sacrificial regalia and garlanded; the horns of oxen might be gilded. As sacrifice sought the harmonisation of the earthly and divine, the victim must seem willing to offer its own life on behalf of the community; it must remain calm and be quickly and cleanly despatched.. Deities were offered victims of their own sex; white and infertile animals for deities of the heavens (di superi) – Jupiter, required a white, castrated ox (bos mas) for the annual consular oath-taking. Di superi with strong connections to the earth, such as Mars, Janus, Neptune and the various genii – including the genius of the Emperor – needed fertile victims, and underworld (Chthonic) gods such as Dis pater and Pluto were given dark, fertile victims. Ceres and other underworld goddesses of fruitfulness were sometimes offered pregnant female animals; Tellus was given a pregnant cow at the Fordicidia festival. Vulcan and Robigo were given reddish-coloured animals; Robigo, a red dog. Demigods and heroes belonged to the heavens and the underworld, and were sometimes given black-and-white victims.
Cults to di superi were held in daylight, and were usually followed by a banquet, at which the cult images of the deity or deities took pride of place on couches and consumed their own portion of the sacrifice (the innards) through the sacrificial fire. Rome's high officials reclined alongside and ate the meat; lesser citizens probably had to provide their own. Underworld deities were given cult at nighttime, and consumed their victims whole, because "the living cannot share a meal with the dead".
Sacrificial offerings could vary according to the context of cult. For example, Lares could be offered spelt wheat and grain-garlands, honey cakes and honeycombs, grapes and first fruits, whenever in season, wine and incense, food that fell to the floor during any family meal, or at their Compitalia festival, honey-cakes and a pig on behalf of the community. Their supposed relatives, the malicious and vagrant Lemures, might be placated with distinctly chthonic midnight offerings of black beans and spring water. Extraordinary circumstances called for extraordinary sacrifice: in one of the many crises of the Second Punic war, Jupiter Capitolinus was promised every animal born that spring, to be rendered after five more years of protection from Hannibal and his allies. Had the gods failed to keep their side of the bargain, sacrifice would have been withheld. In the imperial period, sacrifice was withheld following Trajan's death because the gods had not kept the Emperor safe for the stipulated period. In Pompeii, the genius of the living emperor was offered a bull: presumably a standard practise in Imperial cult, though minor offerings (incense and wine) were also made.
After the Roman defeat at Cannae two Gauls and two Greeks were buried under the Forum Boarium, in a stone chamber "which had on a previous occasion [228 BC] also been polluted by human victims, a practice most repulsive to Roman feelings". Livy avoids the word "sacrifice" in connection with this bloodless human life-offering; Plutarch does not. The rite was apparently repeated in 113 BC, preparatory to an invasion of Gaul. Its religious dimensions and purpose remain uncertain. In the early stages of the First Punic war (264 BC) the first known Roman gladiatorial munus was held, described as a funeral blood-rite to the manes of a Roman military aristocrat. In pre-Christian Rome, the gladiator munus was never considered (or at least, never acknowledged) as a human sacrificial rite, probably because death was not its inevitable outcome or purpose. Even so, the combat was dedicated as an offering to the gods, and was therefore sacrificium in the strict sense of the term. The small woolen dolls called Maniae, hung on the Compitalia shrines, were thought a symbolic replacement for child-sacrifice to Mania, as Mother of the Lares. The Junii took credit for its abolition by their ancestor L. Junius Brutus, traditionally Rome's Republican founder and first consul.
Human sacrifice was officially obnoxious "to the laws of gods and men", and those who practiced it – such as Rome's Carthaginian foes – were irredeemably Other. Rome banned it on several occasions, under extreme penalty; notably in 81 BC, under the aegis of the Lex Cornelia de sicariis et veneficiis. Its alleged practice helped justify the conquest of Gaul, both invasions of Britain and the suppression of the Druids as righteous acts of war: though according to Pliny the Elder, the British clung to the practice for as long as they could. Despite an empire-wide bann under Harian, illicit and covert human sacrifice may have continued in North Africa and elsewhere.
Most state cult took place outside a sanctuary or temple building, within a templum, (sacred space) determined by an augur. Rome itself was an intrinsically sacred space; its ancient boundary (Pomerium) had been marked by Romulus himself with oxen and plough, and it was earthly home and protectorate of its gods. In Rome, the central geographic references for the establishment of an augural templum appears to have been the Via Sacra (Sacred Way) and pomerium (Rome's sacred boundary). Within the templum, magistrates sought divine opinion of proposed official acts through an augur, who read the divine will through observations made within the sacred space, before, during and after an act of sacrifice. Divine disapproval could arise through unfit sacrifice, errant rites (vitium) or an unacceptable plan of action. The magistrate could repeat the sacrifice until favourable signs were seen, consult with his augural colleagues, or abandon the project. Magistrates could use their right of augury (ius augurum) to adjourn and overturn the process of law, but were obliged to base their decision on the augur's observations and advice. For Cicero, this made the augur the most powerful authority in the Late Republic. By his time (mid 1st century BC) augury was supervised by the college of pontifices, whose powers were increasingly woven into the magistracies of the cursus honorum.
Haruspicy was also used in public cult, under the supervision of the augur or presiding magistrate. The haruspices divined the will of the gods through examination of entrails after sacrifice, particularly the liver. They also interpreted omens, prodigies and portents, and formulated their expiation. Most Roman authors describe haruspicy as an ancient, ethnically Etruscan "outsider" religious profession, separate from Rome's internal and largely unpaid priestly hierarchy, essential but never quite respectable. During the mid-to-late Republic, private haruspices were employed by some leading Romans to justify their acts and policies as divinely approvaed: the reformist Gaius Gracchus, the populist politician-general Gaius Marius and his antagonist Sulla, and the "notorious Verres" all used them. The senate and armies used the public haruspices: at some time during the late Republic, the Senate decreed that Roman boys of noble family be sent to Etruria for training in haruspicy and divination. Being of independent means, they would be better motivated to maintain a pure, religious practice for the public good. The motives of private haruspices – especially females – and their clients were officially suspect.
Omens observed within or from a divine augural templum – especially the flight of birds – were sent by the gods in response to official queries; if he deemed the omens unfavourable, a magistrate with ius augurium (the right of augury) could declare the suspension of all official business for the day (obnuntiato). Caesar and Cicero were among those who resorted to this. Conversely, an omen could be re-interpreted as positive.
Prodigies were transgressions in the natural, predictable order of the cosmos – signs of divine anger that portended conflict and misfortune. The Senate decided whether a reported prodigy was false, or genuine and in the public interest, in which case it was referred to the public priests, augurs and haruspices for ritual expiation.In 207 BC, during Rome's Second Punic War the Senate dealt with an unprecedented number of reported prodigies whose expiation would have involved "at least twenty days" of dedicated rites.
The major prodigies of 207 BC included the spontaneous combustion of weapons, the apparent shrinking of the sun's disc, two moons in a daylit sky, a cosmic battle between sun and moon, a rain of red-hot stones, a bloody sweat on statues, and blood in fountains and on ears of corn: all were expiated by sacrifice of "greater victims". The minor prodigies were equally unnatural; sheep became goats, a hen became a cock (and vice-versa) – these were expiated with "lesser victims". The discovery of an androgynous four-year old child was expiated by its drowning and in addition, the holy procession of 27 virgins to the temple of Juno Regina, singing a hymn to avert disaster: a lightning strike during the hymn rehearsals required further expiation. Livy's account of this war – one of the most prolonged and momentous in Rome's history – is punctuated by Rome's dereliction of duty to its gods, inevitably followed by prodigies and portents. Religious restitution is proved only by Rome's victory.
In the wider context of Graeco-Roman religious culture, Rome's earliest reported portents and prodigies stand out as atypically dire. Whereas for Romans, a comet presaged misfortune, for Greeks it might equally signal a divine or exceptionally fortunate birth. By the late Republic, perhaps due to Greek influences, a daytime comet at the murdered Julius Caesar's funeral games confirmed his deification.
Roman treatment of the dead perpetuated their status: in death, as in life, elite Romans were housed in splendour. Votive deposits to deities and the elite dead suggest funeral offerings and banquets in the company of the deceased, an expectation of afterlife and an association between the gods and the noble dead.
The standard Roman funerary inscription is Dis Manibus (to the Manes-gods). Regional variations include its Greek equivalent, theoîs katachthoníois and Lugdunum's commonplace but mysterious "dedicated under the trowel" (sub ascia dedicare).
Burial and commemorative practises of Christian and non-Christians overlap in the later Imperial era; family tombs are shared, and the traditional funeral rites and feast of novemdialis find a part-match in the Christian Consitutio Apostolica. The customary offers of wine and food to the dead continue; St Augustine (following St Ambrose) fears that this too closely resembles the practices of parentalia, and might be a similar cause for drunkenness, but commends funeral feasts as a Christian opportunity to give alms of food to the poor. In 567 AD, Christians were attending not only parentalia but Feralia and Caristia in sufficient numbers for the Council of Tours to forbid them. Other funerary and commemorative practices are very different. Traditional Roman practice spurns the corpse as a ritual pollution; inscriptions note the day of birth and duration of life. The Christian Church fosters the veneration of saintly relics; inscriptions mark the day of death as a transition to "new life".
Romans believed some of their religious customs older than Rome's foundation, some coeval with it and some as native to its allies. Most others were credited to its kings. The Trojan refugee Aeneas, a descendant of Venus was said to have brought the cult of the Lares and Penates to Italy, along with the Palladium; he was received by Evander, a Greek exile from Arcadia who had set up the Ara Maxima (Greatest Altar) to Hercules at the future site of Rome's Forum Boarium and had founded the Lupercalia.
Aeneas' descendants Romulus and his twin brother Remus were divinely fathered on a virgin princess or priestess of Vesta by Mars or Hercules, exposed at birth, and saved by a series of divine or miraculous interventions. When the twins could not agree on the site for their new city, they asked the opinion of the gods through divine augury. The gods sent Romulus more favourable signs; he established his city on the Capitoline Hill, created its sacred boundary, gave it his name, appointed its first senate and organised its armies. Faced with a shortage of marriagable young women, he organised a new religious festival, the Consualia, invited the neighbouring Sabines then kidnapped their daughters. In gratitude for his astounding success in war and to ensure similar success in the future, he founded Rome's first temple to Jupiter Feretrius and offered him the spoils in Rome's first triumph. He became increasingly autocratic, mysteriously disappeared and was deified.
His pious and peaceable successor, Numa was credited with Rome's first religious calendar and religious foundations including the Salii, the priesthoods (flamines) and cults of Jupiter, Mars and Quirinus, the Vestal Virgins and the temple of Janus, whose doors stayed open in times of war. In Numa's time, they were closed. After his death, they remained open until the reign of Augustus.
Each of Rome's legendary or semi-legendary kings was associated with one or more of the religious institutions familiar to the later Republic. Tullus Hostilius and Ancus Marcius devised the fetial priests and their rites. The first "outsider" Etruscan king, Lucius Tarquinius Priscus founded a Capitoline temple to Jupiter, Juno and Minerva which served as a later model for the highest official cult throughout the Roman world. The benevolent, divinely fathered Servius Tullius established the Latin League and built its Aventine Temple to Diana, and instituted the Compitalia to mark his social reforms. His arrogant successor (and murderer) Tarquinius "the Proud" was expelled, and Rome became a Republic, run by annually appointed consuls with divine consent. For Roman historians, the essentials of Republican religion were already established – under good kings or bad – by the Senate and people of Rome.
Rome's ancestors, founders, kings and their reigns are uncertain at best; the city's origins are now thought to be significantly more remote than its historians supposed, in which case the list of kings is too short. Livy places Rome's foundation more than 600 years before his own time. He and his near contemporary Dionysius of Halicarnassus appear to share some common sources, including an earlier history by Quintus Fabius Pictor, of which only a terse summary survives. Republican historians may have sought to interpret such fragments of written history as they possessed, the physical remnants of ancient tombs, shrines, temples and priestly records, the traditional histories of Rome's leading families, and equally important ritual and pre-literate oral traditions of unknown antiquity. Some were already obscure in their meaning and purpose. They sought to address and illuminate the problems and preoccupations of their own times and social class; Rome's religious practices were causal, and its history was a coherent and sacred continuity imperiled by religious negligence and personal ambition. According to Cicero, the Romans considered themselves the most religious of all peoples.
Public cult (sacra publica) was state funded as a matter of public interest (res publica). Public temples and rites were prominent features of Rome's public and political life; the city's rhythms were marked by sacred calendars, and its topology by sacred buildings, shrines and statues. Jupiter's temple would have dominated the Capitol.
Cult was officially recognised as private (sacra privata) or public (sacra publica); the difference is often unclear. Individuals or collegial associations could fund private cult to any divinity or divinities, or donate funds for public rites. Sacra publica could include "domestic" rites, such as those of the public Vestals for parentalia, which was otherwise a sacra privata. Some "public" festivals and the rites of the domus - including those that took place in public places - were defined as privata in part or whole. All were ultimately subject to the supervision of the censor and pontifices.
Rome was a densely built and crowded city. During the Augustan era, it probably housed more than a million people; approximately half were slave or free non-citizen natives, including an unknown number of itinerants and provincials. Less than a quarter of adult males had voting rights – far fewer could actually exercise them. Women had no vote. Government and politics were dominated by Rome's educated, male, landowning military aristocracy. Most Romans had no direct involvement in lawmaking, central government or state religion.  Nevertheless, religion was an effective force in local and national politics.
The links between Rome's religious and political life were vital to its internal governance, diplomacy and development from kingdom, to Republic and to Empire. The powers of Rome's kings, consuls and emperors derived in part through their relationships with the gods. Post-regal politics dispersed the power and authority of the kings more or less equitably among the patrician elite. Plebian political actions eroded the patrician monopoly, made the plebian tribunes sacrosanct, and gained them powers of veto in legislative debate: the plebians still maintained their own distinctive traditions and cults. The Augustan settlement acknowledged the common political and religious interests of all classes. "In a very real sense the senate was the caretaker of the Romans’ relationship with the divine, just as it was the caretaker of their relationship with other humans". All official business was conducted under the divine gaze and auspices.
Temples buildings and shrines within the city commemorated significant political settlements in its development: the Aventine Temple of Diana supposedly marked the founding of the Latin League under Servius Tullius. High-ranking priesthoods provided political opportunity: most were occupied by high-ranking citizens who held – or had held – high political office and influence. Some minor public priesthoods preferred freedmen or slaves, such as the seviri of the Compitalia. The high public profile offered by priesthood was politically useful: likewise, political candidates could fund temples, priesthoods and spectacular public ludi and munera – both of which had strongly religious connotations – to sway electoral decisions. Priesthood offered the divine validation of policy: in 63 BC, Julius Caesar's appointment as pontifex maximus "signaled his emergence as a major player in Roman politics". By 14 AD, Roman religion and politics met in the person of the emperor:
"Because of you we are living, because of you we can travel the seas, because of you we enjoy liberty and wealth." A thanksgiving prayer offered in Naples' harbour to Augustus, on his return from Alexandria, shortly before his death.
Rome had no specifically priestly caste or class: the highest authority in any community usually sponsored its cults and sacrifices, and often officiated as its priest. Heads of households, ruling consuls, military leaders and emperors all held priestly obligations to their subordinates and their deities. However, a priest derived his authority directly from the eternal divine. A magistrate derived his strictly temporary powers from his electorate: his election, his office and his actions while in office must meet with divine approval. The interdependence and separation of priestly and civil authority are evident in the Regal era, when a rex sacrorum (king of the sacred rites) is thought to have supervised regal and state rites, in conjunction with the king (rex) or in his absence. The abolition of monarchy eroded the executive authority of the rex sacrorum: the collegial power and influence of the Republican pontifices increased. By the late Republican era, the rex sacrorum had become a relatively obscure priesthood with an entirely symbolic title: his religious duties included the daily, ritual announcement of festivals and priestly duties within two or three of them but little else. The most important of his former priestly roles – the supervision of the Vestals and their rites – fell to the more politically powerful and influential pontifex maximus. Assistants and acolytes were usually promoted or co-opted from within the community. Religious professionals such as haruspices, oracles and other diviners were available for consultation if need arose.
The earliest pontifices were probably the flamines (s. flamen): the major flamines, dedicated to Jupiter, Mars and Quirinus, and later, to Capitoline Jupiter, Juno and Minerva, were traditionally drawn from patrician families. Twelve lesser flamines were each dedicated to a single deity. A flamen's was a lifetime appointment and his activities were restricted by strict ritual prohibitions; Jupiter's flamen in particular had virtually no simultaneous capacity for an active political or military career. Nevertheless, co-option to the priesthood offered high public profile and political influence, and most priesthoods could be surrendered without penalty. An ex-priest enjoyed certain privileges and immunities, even in exile. Therefore the number and kind of religious offices allowed an individual or his family were limited by law. Religious law informed and in some cases overrode political decisions and must be explained, expounded and rigorously administered by qualified professionals, not by politicians for personal gain. For those who had reached their goal in the Cursus honorum, permanent priesthood was best sought or granted after a lifetime's service in military or political life, or preferably both: it was a particularly honourable and active form of retirement which fulfilled an essential public duty. For those of less elevated status, the minor priesthoods of predominantly plebian cults offered a high local profile and political opportunities.
During the Imperial era, priesthood of the Imperial cult offered provincial elites full Roman citizenship and public prominence beyond their single year in religious office; in effect, it was the first step in a provincial cursus honorum. In Rome, the same role was performed by the Arval Brethren, once an obscure Republican priesthood dedicated to several deities, then co-opted by Augustus as part of his religious reforms. The Arvals offered prayer and sacrifice to Roman state gods at various temples for the continued welfare of the Imperial family on their birthdays, accession anniversaries and to mark extraordinary events such as the quashing of conspiracy or revolt. Every January 3 they consecrated the annual vows and rendered any sacrifice promised in the previous year, provided the gods had kept the Imperial family safe for the contracted time.
Rome's citizen-soldiers were supposed to embody the values of the society they were sworn to defend; from at least the 4th century BC, "an aggressive and efficient military apparatus" was the core of Rome's expansion and success. At the same time, it was a potent agency in Rome's social, political and religious development.
Expansion was made possible by the integration of the allied nobility and its clients into Rome's government, religious and military apparatus and was achieved through a combination of personal and collective virtus (roughly, "manly virtue") and the divine will: lack of virtus, civic or private negligence in religio and the growth of superstitio provoked divine wrath and led to miltary disaster. Rome's military success was the touchstone of its special relationship with the gods, and to Jupiter Capitolinus in particular; on the day of their triumph, triumphal generals were dressed as the god, and laid their victor's laurels at his feet.
The greatest virtus lay in the devotio of willing self-sacrifice to the gods of the underworld for the greater good, in which the consular Decii – father, son and (possibly) grandson – were considered exemplary. Livy offers a detailed account of the first in this remarkable series. Before the battle, Decius is granted a prescient dream that reveals his fate. When he offers sacrifice, the victim's liver appears "damaged where it refers to his own fortunes". Otherwise, the haruspex tells him, the sacrifice is entirely acceptable to the gods. Decius is therefore not only destined to die; he is obliged to do so in discharge of his vows – this will fulfill the ominous sign in the victim's liver, and remove all possible taint from the sacrifice. He commits himself and the enemy to the dii Manes and Tellus, charges alone and headlong into the enemy ranks, and is killed. His courage inspires his men to victory. Had he done otherwise, his pre-battle sacrificial offering would have been void, with possibly disastrous consequences.
Roman camps followed a standardised pattern for defense and religious ritual. The commander's headquarters stood at the centre; he took the auspices on a dais in front. A small building behind housed the legionary standards, the divine images used in religious rites and in the Imperial era, the image of the ruling emperor. One camp titles this shrine as a Capitolium. The most important camp-offering appears to have been the suovetaurilia performed before a major, set battle. A ram, a boar and a bull were ritually garlanded, led around the outer perimeter of the camp (a lustratio exercitus) and in through a gate, then sacrificed: Trajan's column shows three such events from his Dacian wars. The perimeter procession and sacrifice suggest the entire camp as a divine templum; all within are purified and protected. 
Legionary camps were Rome in miniature. Each had its own religious personel; standard bearers, priestly officers and their assistants, and housekeepers of shrines and images. A senior magistrate-commander (sometimes even a consul) headed it, his chain of subordinates ran it and a sometimes ferocious system of training and discipline ensured that every citizen-soldier knew his duty. As in Rome, whatever gods he served in his own time seem to have been his own business; legionary forts and vici included shrines to household gods, personal deities and deities otherwise unknown. From the earliest Imperial era, citizen legionaries and provincial auxiliaries gave cult to the emperor and his familia on Imperial accessions, anniversaries and their renewal of annual vows. They celebrated Rome's official festivals in absentia, and had the official triads appropriate to their function – in the Empire, Jupiter, Victoria and Concordia were typical. By the early Severan era, the military also offered cult to the Imperial divi, the current emperor's numen, genius and domus (or familia), and special cult to the Empress as "mother of the camp." The near ubiquitous legionary shrines to Mithras of the later Imperial era were not part of official cult until Mithras was absorbed into Solar and Stoic Monism as a focus of military concordia and Imperial loyalty.
Roman mos maiorum restricted the social, political and religious capacities of Roman women. The few Roman literary sources to address the subject of women in relation to religio represent some as paragons of Roman virtue but more often as constitutionally prone to self-indulgent religious enthusiasms, novelties and the seductions of superstitio. Bona Dea's festival rites excluded men entirely; this seems to have been cause for prurient male speculation, and a scandalous, impious intrusion by Publius Clodius Pulcher. Most cults and ludi did not forbid the presence of women. Some specifically required it, but their active participation was limited. In almost all public cult, priesthood was a male preserve; family cults were headed by the paterfamilias.
The most important exception was the public cult to Vesta, goddess of the hearth of the Roman state and its vital flame, served by six virgin priestesses. In one strand of Rome's foundation myth, Romulus and Remus were fathered by Mars or Hercules on a Vestal virgin of royal blood. Another tradition held that Rome's sixth king was fathered by a disembodied phallus on a virgin slave-girl who served at the royal hearth: the cult objects stored in Vesta's temple included a phallus and the Penates and Lares of the Roman state. A girl chosen to be a Vestal Virgin achieved unique religious distinction, public status and privileges, but was constrained during her thirty-year office by ritual prohibitions and obligations not even a flamen of Jupiter Capitolinus could match: a Vestal polluted by the loss of her viginity while in office was buried alive.
The Vestals "represented a peculiarly extreme version of the connection between the religious life of the home and of the community". They were directly involved in the rites of Parilia, Parentalia, Fordicidia, and they prepared essential sacrificial materials for others. A Vestal's dress presented her simultaneously as virgin bride and daughter, Roman matron and wife. She held some of the legal privileges of a male head of household but was housed with her peers under the immediate supervision of the chief Vestal and ultimately of the pontifex maximus. Vesta's virgin priestesses "seem to have been an exception to most rules of Roman life".
Augustus' religious reformations raised the funding and public profile of the Vestals. They were given high status seating at games and theatres. The emperor Claudius appointed them as priestesses to the cult of the deified Livia (wife of Augustus). They seem to have retained their religious and social distinctions at least until the Christian emperor Gratian refused the office of pontifex maximus and began the dissolution of their order: his successor Theodosius I extinguished Vesta's sacred fire and vacated her temple.
The mos maiorum established the dynastic authority of the citizen-paterfamilias ("the father of the family" or the "owner of the family estate"), his obligations to family and community and his priestly duties to his lares, domestic penates, ancestral genius and any other deities with whom he or his family held an interdependent relationship. His own dependents, who included his slaves and freedmen, owed cult to his genius.
As head of his household, pater familias was also its senior priest. He offered daily cult to his lares and penates, and to his di parentes/divi parentes, in domestic shrines and in the fires of the household hearth. His wife (mater familias) was responsible for the household's cult to Vesta. Other dependents and household officials seem to have particular responsibilities; in rural estates, the bailiff seems to been responsible for at least some of the household shrines (lararia) and their deities. Household cults had state counterparts. In Vergil's Aeneid, Aeneas brought the Trojan cult of the lares and penates from Troy, along with the Palladium which was later installed in the temple of Vesta.
Genius was the essential spirit and generative power – depicted as a serpent or as a perennial youth, often winged – within an individual and their clan (gens (pl. gentes). A paterfamilias could confer his name, a measure of his genius and a role in his household rites, obligations and honours upon those he fathered or adopted. His freed slaves owed him similar obligations.
Rome's oldest surviving religious calendars date to the late Republic but the most detailed are Augustan and later. These seem to represent a broad, official grouping of sacred categories. Some, titled in capital letters, are generally assumed the more important and ancient. Others, titled in small letters, may have been less important or more recent. No single example can be regarded as authoritative; different localities may have followed their own ritual and interpretive traditions. "The richest source of all is Ovid's Fasti, a witty verse account of the first six months of the Roman calendar and its rituals," written during the reign of the emperor Augustus. There can be little doubt that some festivals, such as Saturnalia and Consualia, would have traditionally included broad humour and burlesque, but Ovid's Fasti is an artistic work, imaginative, high-minded, entertaining and scurrilous by turns. The less a particular festival was understood, the greater the opportunities for its cumulative reinterpretation and reinvention. An understanding of its "'original' significance [is therefore] not just difficult, but close to impossible".
Work days (nefasti) on the calendars are outnumbered by festival days (fasti), when official business was suspended. Some festivals last for a single day or less, others for several. The calendars mark the passage of time as sacred, communal and official. They also represent the celebrations, traditions and values of specific classes and occupations, each with its own traditions and values. For example, Saturnalia ends the year and universaly allows a temporary reversal of status quo between master and slave: Parilia begins the pastoral year and involves both "private" cult and the state Vestals. Compitalia is agricultural, local, plebian and servile but its cult to the Lares has a state counterpart. Two Equiria festivals are dedicated to Mars. One purifies the Roman army in his name. In the other, the Equus october, winning horse of his October festival's chariot race, is sacrificed then fought over between the iuvenes of the Regia and Subura. There is no reason to assume that all Romans were involved with all festivals; some may have required only the presence and rites of their priests and acolytes.
Other public festivals were held at need; a triumph was celebrated as an important social, political and religious event. Public ludi (games) and Gladiator contests had strong religious dimensions and popular appeal. They were gradually brought under the control and subsidy of the State, and later, the Imperial house. In the Imperial period, additional festivals and games celebrated Imperial accessions and anniversaries. The Secular games were religious athletic events held at irregular intervals, traditionally once only in about every century, to mark the beginning of a new saeculum (era); they appear to have fallen into abeyance during the late Republic, but were revived by Augustus.
Objects of Roman cult range from the myriad characteristics of deities to their personifications of abstract ideas, places, objects and personal virtues. Cults are meticulously formulaic and legalistic in character but divine spheres, characters and functions expand, overlap and are redefined. New deities and changes in cult are carefully embedded within what already exists; cult is both conservative and resilient.
Rome's religious identity and deities reflect its diverse multicultural origins. The perceived equivalence of deities was fundamental to political, cultural and religious coherence in the Roman super-state. No single cult, or combination of cults represents an original or essential core of Roman religious identity: in legend, Mars or Hercules father Romulus and Remus with Vesta's cult already in place. Jupiter's temple is built after the city's foundation by augury, not before it: Roman Quirinus has not yet come into being, let alone Romulus-Quirinus. Juno is a foreign latecomer, Apollo even later. Roman religion maintains a broad, inclusive and flexible network of practices which requires neither doctrinal schema nor any systematic hierarchy of the divine.
Jupiter is the dominant deity of the Roman state throughout the regal, Republican and Imperial eras because the state constructs him as such. He grants Rome supremacy because he, the most powerful of all deities, is honoured more by the Romans than by all others. His historic identity is far from clear. He may have begun as a sky-god, concerned mainly with wine festivals and associated with the sacred oak on the Capitol; if so, he then develops a twofold character. He receives the spolia opima and becomes a god of war; as Stator he makes the armies stand firm and as Victor he gives them victory – who becomes the intermediary feminine personification Victoria. As the sky-god, he is the first resort as a divine witness to oaths.. Mars is a deity of both agriculture and war; and the Colline deity, Quirinus, may have been his equivalent. Jupiter, Mars and Quirinus are described as the early Triad of Roman state religion; collectively and individually, they are Roman gods, associated with the agricultural economy, social organisation and success in war of a distinctively Roman state before, during and after its transition from monarchy to Republic. Jupiter is "the fount of the auspices upon which the relationship of the city with the gods rested": as such, he personifies the divine authority of Rome's highest offices, internal organization and external relations. 
Any relationship between these "elite" deities and those favouring lower status groups is equally unclear. From the early Republic, and possibly before, plebians, freedmen and slaves gave cult to an agricultural triad of Ceres, Liber, and Libera, and served as their priests. Their games had strong traditional and priestly associations with their supposed regal patron and benefactor Servius Tullius, the Lares of the Compitalia festival and cult to Fortuna Primigenia.
Rome offers no native creation myth and very little native mythography to explain the character of its deities, their mutual relationships or their interactions with the human world. Greek narrative models were certainly available to Romans, and later Roman pantheistic hierarchies have a distinctively Greek character, part literary-mythographic, part philosophical; but none of this seems to have had a significant effect on cult practice. The gods in general are the di immortales, who can be assumed numberless. The development of a semi-official pantheon begins against the background of extreme political, social and religious instability of the Late Republican era, and is motivated by politico-religious ideology, rather than theology. The accumulated diversity of cult throughout the Roman world is subject to re-interpretation as a potentially coherent, purposeful and peaceful whole. Under the Empire, these cults continue, politically subordinate to the new order. Where loyalty to the state is implicit, no divine hierarchy need be constructed or enforced.
At best, the ancient and venerable Greek Olympians offer an incomplete and potentially misleading model of Roman practice. At any given time, the impressive, complex and costly rites to the deities of the Roman state are far outnumbered by daily, commonplace cults to domestic and personal deities, and the cults of Rome's internal, non-elite communities. Thus, a citizen-native of Bordeaux travels to Italy and consults the Sibyl at Tibur, but cannot forget his own goddess:
I wander, never ceasing to pass through the whole world, but I am ﬁrst and foremost a faithful worshiper of Onuava. I am at the ends of the earth, but the distance cannot tempt me to make my vows to another goddess. Love of the truth brought me to Tibur, but Onuava’s favorable powers came with me. Thus, divine mother, far from my home-land, exiled in Italy, I address my vows and prayers to you no less..
See also Background to the Roman Imperial cult.
The iconography of Empire invests local and provincial deities as aspects of a divine Imperial order. Egyptian statuettes equip Horus, Bes, and Anubis as Roman generals; Augustus is shown as a divine pharaoh.
"The architecture of the ancient Romans was, from first to last, an art of shaping space around ritual." Roman religion was not confined to temples and shrines. 
The Romans offered no distinct or exclusive category of cult practices as "Roman religion". Some cult practices were funded by the state, some were not. Some deities were regarded as indigenous, others as "foreign"; the romanitas of their cults served an inclusive Roman identity. Roman cult emphasised the collective, communal act of worship, not the individual worshiper.
Excessive devotion and enthusiastic emotionalism in religious observance were superstitio, in the sense of "doing or believing more than was necessary". This was often "seen to be motivated by an inappropriate desire for knowledge". Women were considered particularly prone to excessive religiosity.. Some superstitiones could be condemned as fraudulent, others as destabilising or potentially destructive magic. However, the borders between acceptable and unacceptable practices were permeable and negotiable.
"In vulgar tradition (more vulgari)...a magician is someone who, because of his community of speech with the immortal gods, has an incredible power of spells (vi cantaminum) for everything he wishes to." Apuleius, Apologia, 26.6.
Magic was an attempt to control the gods: this was the utmost impiety. In the Graeco-Roman world, its practitioners were known as Magi – a title of Persian priests. Pliny the Elder's Natural History includes a thoroughly skeptical "History of magical arts" from their supposed Persian origins to the ill-fated emperor Nero's vast and futile expenditure on research into magical practices. In Lucan's Pharsalia, Pompey's doomed and wretched son, awaiting the battle of Pharsalus and convinced that "the gods of heaven knew too little" of the outcome, resorts to the disgusting necromancy of Erichtho, the Thessalian witch who inhabits deserted graves and feeds on rotting corpses. Erichtho and those who use her services offend the natural order of gods, mankind and destiny.
Archaeological evidence confirms a widespread use of so-called curse tablets (defixiones) and magical papyri. Around 250 defixiones have been recovered from urban and rural Britain, and none seem produced by, or on behalf of elite Romano-Britons. Some seek straightforward, usually gruesome revenge, but others appeal for divine redress of wrongs in terms familiar to any Roman magistrate. Some promise a portion of the value of lost or stolen property to the deity if the property is returned: in general, the money values are low. Presumably, those without ready resort to human law and justice must appeal directly to the gods, as the divine source of justice in human affairs.
Some individuals sought to divine the future, or influence it through magic, with help from "private" diviners, or with direct help from chthonic deities who functioned at the margins of Rome's divine and human communities. The living might gain their favour and help with an offering of the right kind, made well away from the public gaze, during the hours of darkness. Burial grounds and isolated crossroads were among the likely portals. The offering was entirely consumed by the deity, either through the earth itself or in the flames of the sacrificial fire. According to Scheid, the living never shared food with the gods of the dead.
By the end of the regal period Rome had developed into a city-state, with a large plebian, artisan class excluded from the old patrician gentes and from the state priesthoods. The city had commercial and political treaties with its neighbours; according to tradition, Rome's Etruscan connections established a temple to Minerva on the predominantly plebian Aventine; she became part of a new Capitoline triad of Jupiter, Juno and Minerva, installed in a Capitoline temple, built in an Etruscan style and dedicated in a new September festival, Epulum Jovis. These are supposedly the first Roman deities whose images were adorned, as if noble guests, at their own inaugural banquet.
Rome's diplomatic agreement with her neighbours of Latium confirmed the Latin league and brought the cult of Diana from Aricia to the Aventine. and established on the Aventine in the "commune Latinorum Dianae templum": At about the same time, the temple of Jupiter Latiaris was built on the Alban mount, its stylistic resemblance to the new Capitoline temple pointing to Rome's inclusive hegemony. Rome's affinity to the Latins allowed two Latin cults within the pomoerium: and the cult to Hercules at the ara maxima in the Forum Boarium was established through commercial connections with Tibur. and the Tusculan cult of Castor as the patron of cavalry found a home close to the Forum Romanum: Juno Sospes and Juno Regina were brought from Italy, and Fortuna Primigenia from Praeneste. In 217, Venus was brought from Sicily and installed in a temple on the Capitoline hill.
The disasters of the early part of Rome's second Punic War were attributed, in Livy's account, to a growth of superstitious cults, errors in augury and the neglect of Rome's traditional gods; their anger (ira deorum) was signaled by a host of potents and prodigies but expressed directly by Rome's defeat at Cannae (216 BC). The Sibilline books were consulted. They recommended a general vowing of the ver sacrum and in the following year, the burial of two Greeks and two Gauls; not the first or the last of its kind, according to Livy.
Rome's military-political brought an increasing number of deities into Roman cult. In 206 BC the Sibylline books recommended the introduction of cult to the aniconic Magna Mater (Great Mother) from Pessinus, installed on the Palatine in 191 BC. The mystery cult to Bacchus followed, and grew to such proportions that it had to be suppressed by decree of the Senate in 186 BC. Greek deities were brought within the sacred pomerium, where temples were dedicated to Juventas (Hebe) in 191 BC, Diana (Artemis) in 179 BC, Mars (Ares) in 138 BC), and Bona Dea, equivalent to Fauna, the female counterpart of the rural Faunus, supplemented by the Greek goddess Damia. Further Greek influences on cult images and types represented the Roman Penates as a form of the Greek Dioscuri. The military-political adventurers of the Later Republic introduced the Phrygian goddess Ma (identified with Roman Bellona, the Egyptian mystery-goddess Isis and Persian Mithras.
The spread of Greek literature, mythology and philosophy offered Roman poets and antiquarians a model for the interpretation of Rome's festivals and rituals, and the embellishment of its mythology. Ennius translated the work of Graeco-Sicilian Euhemerus, who explained the genesis of the gods as apotheosized mortals. In the last century of the Republic, Epicurean and particulary Stoic interpretations were a preoccupation of the literate elite, most of whom held - or had held - high office and traditional Roman priesthoods; notably, Scaevola and the polymath Varro. For Varro - well versed in Euhemerus' theory - popular religious observance was based on a necessary fiction; what the people believed was not itself the truth, but their observance led them to as much higher truth as their limited capacity could deal with. Whereas in popular belief deities held power over mortal lives, the skeptic might say that mortal devotion had made gods of mortals, and these same gods were only sustained by devotion and cult. As to any original meanings, purposes and mechanisms of these rites and observances, Varro confessed himself quite baffled.
Just as Rome itself claimed the self-evident favour of the gods, so could individual Romans. In the mid-to-late Republican era, and probably much earlier, many of Rome's leading clans acknowledged a divine or semi-divine ancestor and laid personal claim to their favour and cult, along with a share of their divinity. Most notably in the very late Republic, the Julii claimed Venus Genetrix as ancestor; this would be one of many justifcations for the Imperial cult. The claim was further elaborated and justified in Vergil's poetic, Imperial vision of the past.
In the late Republic, the Marian reforms lowered an existing property bar on conscription and increased the efficiency of Rome's armies but made them available as instruments of political ambition and factional conflict. The consequent civil wars led to changes at every level of Roman society. Augustus' principate established peace and subtly transformed Rome's religious life – or, in the new ideology of Empire, restored it (see below).
Towards the end of the Republic, religious and political offices became more closely intertwined; the office of pontifex maximus became a de facto consular prerogative. Augustus was personally vested with an extraordinary breadth of political, military and priestly powers; at first temporarily, then for his lifetime. He acquired or was granted an unprecedented number of Rome's major priesthoods, including that of ponifex maximus; as he invented none, he could claim them as traditional honours. His reforms were represented as adaptive, restorative and regulatory, rather than innovative; most notably his elevation (and membership) of the ancient Arvales, his timely promotion of the plebian Compitalia shortly before his election and his patronage of the Vestals as a visible restoration of Roman morality. Augustus obtained the pax deorum, maintained it for the rest of his reign and adopted a successor to ensure its continuation. This remained a primary religious and social duty of emperors, though few actually fulfilled it.
The Roman Empire expanded to include different peoples and cultures; in principle, Rome followed the same inclusionist policies that had recognised Latin, Etruscan and other Italian peoples, cults and deities as Roman. Those who acknowledged Rome's hegemony retained their own cult and religious calendars, independent of Roman religious law. Newly municipal Sabratha built a Capitolium near its existing temple to Liber Pater and Serapis. Autonomy and concord were official policy, but new foundations by Roman citizens or their Romanised allies were likely to follow Roman cultic models. Romanisation offered distinct political and practical advantages, especially to local elites. All the known effigies from the 2nd cent. AD forum at Cuicul are of emperors or Concordia. By the middle of the first century AD, Gaulish Vertault seems to have abandoned its native cultic sacrifice of horses and dogs in favour of a newly established, Romanised cult nearby: by the end of that century, Sabratha’s so-called tophet was no longer in use. Colonial and later Imperial provincial establishments were dedicated to Rome's Capitoline Triad – it was a logical choice, not a centralised legal requirement. Major cult centres to "non-Roman" deities continued to prosper: notable examples include the magnificent Alexandrian Serapium, the temple of Aesculapeus at Pergamum and Apollo's sacred wood at Antioch.
The overall scarcity of evidence for smaller or local cults does not always infer their neglect; votive inscriptions are inconsistently scattered throughout Rome's geography and history. Inscribed dedications were an expensive public declaration, one to be expected within the Graeco-Roman cultural ambit but by no means universal. Innumerable smaller, personal or more secretive cults would have persisted and left no trace.
Military settlement within the empire and at its borders broadened the context of Romanitas. Rome's citizen-soldiers set up altars to multiple deities, including their traditional gods, the Imperial genius and local deities – sometimes with the usefully open-ended dedication to the diis deabusque omnibus (all the gods and goddesses). They also brought Roman "domestic" deities and cult practices with them.By the same token, the later granting of citizenship to provincials and their conscription into the legions brought their new cults into the Roman military.
Traders, legions and other travellers brought home cults originating from Egypt, Greece, Iberia, India and Persia. The cults of Cybele, Isis, Mithras, and Sol Invictus were particularly important. Some of those were initiatory religions of intense personal significance, similar to Christianity in those respects.
In the early Imperial era, a ruling princeps (lit. "first head of the Senate) was offered genius-cult as the symbolic paterfamilias of Rome. His cult had further precedents: popular, unofficial cult offered to powerful benefactors in Rome: the kingly, god-like honours granted a Roman general on the day of his triumph; and in the divine honours paid to Roman magnates in the Greek East from at least 195 BC.
The deification of deceased emperors had precedent in Roman domestic cult to the dii parentes (deified ancestors) and the mythic apotheosis of Rome's founders. A deceased emperor granted apotheosis by his successor and the Senate became an official State divus (divinity). Members of the Imperial family could be granted similar honours and cult; an Emperor's deceased wife, sister or daughter could be promoted to diva (female divinity).
The first and last Roman known as a living divus was Julius Caesar, who seems to have aspired to divine monarchy; he was murdered soon after. Greek allies had their own traditional cults to rulers as divine benefactors, and offered similar cult to Caesar's successor, Augustus, who accepted with the cautious proviso that expatriate Roman citizens refrain from such worship; it might prove fatal. By the end of his reign, Augustus had appropriated Rome's political apparatus – and most of its religious cults – within his "reformed" and thoroughly integrated system of government. Towards the end of his life, he cautiously allowed cult to his numen. By then the Imperial cult apparatus was fully developed, first in the Eastern Provinces, then in the West.Provincial Cult centres offered the amenities and opportunities of a major Roman town within a local context; bathhouses, shrines and temples to Roman and local deities, amphitheatres and festivals. In the early Imperial period, the promotion of local elites to Imperial priesthood gave them Roman citizenship.
In an empire of great religious and cultural diversity, the Imperial cult offered a common Roman identity and dynastic stability. In Rome, the framework of government was recognisably Republican. In the Provinces, this would not have mattered; in Greece, the emperor was "not only endowed with special, super-human abilities, but... he was indeed a visible god" and the little Greek town of Akraiphia could offer official cult to "liberating Zeus Nero for all eternity".
In Rome, state cult to a living emperor acknowledged his rule as divinely approved and constitutional. As princeps (first citizen) he must respect traditional Republican mores; given virtually monarchic powers, he must restrain them. He was not a living divus but father of his country (pater patriae), its pontifex maximus (greatest priest) and at least notionally, its leading Republican. When he died, his ascent to heaven, or his descent to join the dii manes was decided by a vote in the Senate. As a divus, he could receive much the same honours as any other state deity – libations of wine, garlands, incense, hymns and sacrificial oxen at games and festivals. What he did in return for these favours is unknown, but literary hints and the later adoption of divus as a title for Christian Saints suggest him as a heavenly intercessor. Until he died, official cult to an emperor in Rome was directed to his genius; a small number refused this honour and there is no evidence of any emperor receiving more than that. In the crises leading up to the Dominate, Imperial titles and honours multiplied, reaching a peak under Diocletian. Emperors before him had attempted to guarantee traditional cults as the core of Roman identity and well-being; refusal of cult undermined the state and was treasonous.
Christian apologists identified cult to Emperors as a particularly impious instrument of persecution. It therefore became a focus of theological and political debate during the ascendancy of Christianity under Constantine I. The emperor Julian failed to reverse the declining support for Rome's traditional cults: Theodosius I adopted Christianity as the Imperial State religion. Officially, the "Imperial cult" was abandoned, along with all cults other than Imperially sanctioned forms of Christianity.
After the Great Fire of Rome in 64 AD, Emperor Nero accused the Christians as convenient scapegoats who were later persecuted and killed. From that point on, Roman official policy towards Christianity tended towards persecution. During the various Imperial crises of the Third century, “contemporaries were predisposed to decode any crisis in religious terms”, regardless of their allegiance to particular practices or belief systems. Christianity drew its traditional base of support from the powerless, who seemed to have no religious stake in the well-being of the Roman State; their religious negligence and self-indulgent superstitio threatened its very existence.
Decius succeeded (or murdered and usurped) his predecessor Philip the Arab; perhaps to secure a succession of doubtful validity, he justified his position as the "restorer and saviour" of Empire and its religio. In the wake of religious riots in Egypt, he decreed that all subjects of the Empire must actively seek to benefit the state through witnessed and certified sacrifice to "ancestral gods" or suffer a penalty: only Jews were exempt. The Decian edict required that refusal of sacrifice be tried and punished at proconsular level. Apostasy was sought, rather than capital punishment. A year after its due deadline, the edict was allowed to expire and shortly after this, Decius himself died. The Decian edict appealed to whatever common mos maiores might reunite a politically and socially fractured Empire. Within its multitude of cults, no ancestral gods need be specified by name. The fulfillment of this sacrificial obligation by loyal subjects would define them and their gods as Roman. Yet the Decian edict represents a significant departure from precedent. Most oaths of loyalty were collective; the Decian oath has been interpreted as a design to root out individual subversives and suppress their cults.
The first edict of Valerian (253-60) singled out the largest and most stubborn of these cults: he outlawed Christian assembly and urged Christians to sacrifice to Rome's traditional gods. His second edict acknowledged Christianity as a direct threat to the Imperial system – one not yet at its heart but possibly close to it, among Rome’s equites and Senators. His reign ended in his capture and utter disgrace; a divine judgement, according to Christian apologists. The majority of Rome’s elite continued to observe various forms of inclusive Hellenistic monism; Neoplatonism in particular accommodated the miraculous and the ascetic within a traditional Graeco-Roman cultic framework. In the forty years of peace following Valerian’s death, the Christian church grew stronger. Its literature and theology acquired a higher social and intellectual profile, due in part to its own search for political toleration and theological coherence. While Origen could discuss theological issues with traditionalist elites within a common Neoplatonist frame of reference and write to Philip the Arab in similar vein, Hippolytus could recognise a “pagan” basis in Christian heresies. Church unity was far from easy to achieve; Paul of Samosata, Bishop of Antioch was deposed by a synod of 268 for "dogmatic reasons – his doctrine on the human nature of Christ was rejected – and for his lifestyle, which reminded his brethren of the habits of the administrative elite". The reasons for his deposition were widely circulated among the churches. Meanwhile Aurelian (270-75) appealed for harmony among his soldiers (concordia militum), stabilised the Empire and its borders and successfully established an official, Hellenic form of unitary cult to the Palmyrene Sol Invictus in Rome's Campus Martius.
The issue of Imperially enforced sacrifice divided Christian communities. Their bishops could interpret this as hollow and harmless necessity – and comply themselves – or else resist and expect the same of their flocks. Penance, rather than perfection of faith, became central to Christian ethics.
From 303 AD, Diocletian issued several edicts against Christianity. The first "ordered the destruction of church buildings and Christian texts, forbade services to be held, degraded ofﬁcials who were Christians, re-enslaved imperial freedmen who were Christians, and reduced the legal rights of all Christians. But physical or capital punishments were not imposed on them." Soon after, several Christians suspected of attempted arson in the palace were executed. A second edict threatened Christian priests with imprisonment and a third offered them freedom if they performed sacrifice. The edict of 304 enjoined universal sacriﬁce in much the same terms as the Decian edict had done; but the numbers of Christians had grown enough to make its target much more apparent. Many complied under threat of penalty, but some local communities were by now not only pre-dominantly Christian, but powerful and influential. Diocletian's successor Galerius maintained anti-Christian policy until his deathbed revocation in 311, when he asked Christians to pray for him. "This meant an ofﬁcial recognition of their importance in the religious world of the Roman empire, although one of the tetrarchs, Maximinus Daia, still oppressed Christians in his part of the empire up to 313." Constantine I (324-337) ended the persecutions by establishing religious freedom through the Edict of Milan in 313. He later convened the historic First Council of Nicaea in 325, a year after ending the civil war of 324 and emerging as the victor in the war of succession. This First Council of Nicaea was formed to oppose Arius who had challenged the deity of Jesus Christ. The result was the branding of Arianism as a heresy. Christianity, as opposed to other religious groups, became the official state religion of the Roman empire on February 27, 380 through an edict issued by Emperor Theodosius I in Thessalonica and published in Constantinople. All cults, save Christianity, were prohibited in 391 by another edict of Theodosius I. Destruction of temples began immediately. When the Western Roman Empire ended with the abdication of Emperor Romulus Augustus in 476, Christianity survived it, with the Bishop of Rome as the dominant religious figure, but see also Pentarchy.
When Constantine became the sole Roman Emperor in 324, Christianity became the leading religion of the empire. After the death of Constantine in 337, two of his sons, Constantius II and Constans took over the leadership of the empire. Constans, ruler of the western provinces, was, like his father, a Christian. In 341, he decreed that all pre-Christian Graeco Roman worship and sacrifice should cease; warning those who still persisted in practising ancient Graeco-Roman polytheism with the threat of the death penalty.
Lay Christians took advantage of new anti-Graeco-Roman polytheism laws by destroying and plundering the temples. Temples that survived were converted into Christian churches: the Pantheon is the most notable example, having once been a temple to all the gods and later, removing the statues of the so-called 'pagan' gods and replacing them with Christian saints, becoming a church in honor of their own one god. Many of the buildings in the Roman Forum were similarly converted, preserving the structures if not their original intent.
Later on, the emperor Julian the Apostate attempted to reverse the process of Christianization and bring back the native forms of polytheism, but his death in Persia caused the empire to once again fall under the power of Christian control, this time permanently.
Roman historians presumed the Roman religion as indigenous and conservative in its essentials; this was generally accepted by medieval and renascence scholars. Later historians received, collated and filtered Roman scholarship through their preferred theories of social and religious development.
In the 19th and early 20th centuries, magic, fetishism, animism, and totemism were often assumed to be the first and most primitive forms of any religion. Rome's historically reported practice was supposed to contain "many survivals from a very early form of religious thought prior to the development of the characteristic Roman attitude of mind", such as the numen. Broadly speaking, these theories held that as any society developed and extended, so did its concepts and attendant deities. Isolated agricultural societies produced divinities of huts, ploughs, first furrow and harvest; their prosperity led to the trading of commodities and ideas with similar communities. Further development involved status and labour divisions, producing warrior castes, peasantry and more deities, with priests and festivals to serve them - and so on. A mature society achieved urban nationhood, complete with bureaucracy, conservatism and a capacity for abstract thought. This same higher faculty also produced skepticism, which sat uneasily alongside the fossilised rites whose original nature, purpose and meaning might be entirely forgotten. This scenario takes Rome's traditional Religions as progressively drained of "real meaning", as in the Punic crises when Rome's "failing native divinities" could only be refreshed by foreign gods. These deities inspire passionate cult, and some have mysteries attached - usually Greek but later, during the crises of the Later Republic, "even Egyptian... and Persian". Some are too passionate and are subsequently ejected. What is and what is not a "Roman religion" seems clear enough to Romans. Modern scholarship is less certain what the religions of ancient Rome meant to them.