Repentance is a change of thought and action to correct a wrong and gain forgiveness from a person who is wronged. In religious contexts it usually refers to confession to God, ceasing sin against God, and resolving to live according to religious law. It typically includes an admission of guilt, a promise or resolve not to repeat the offense; an attempt to make restitution for the wrong, or in some way to reverse the harmful effects of the wrong where possible.
In Biblical Hebrew, the idea of repentance is represented by two verbs: שוב shuv (to return) and נחם nicham (to feel sorrow). In the New Testament, the word translated as 'repentance' is the Greek word μετάνοια (metanoia), "after/behind one's mind", which is a compound word of the preposition 'meta' (after, with), and the verb 'noeo' (to perceive, to think, the result of perceiving or observing). In this compound word the preposition combines the two meanings of time and change, which may be denoted by 'after' and 'different'; so that the whole compound means: 'to think differently after'. Metanoia is therefore primarily an after-thought, different from the former thought; a change of mind accompanied by regret and change of conduct, "change of mind and heart", or, "change of consciousness". A description of repentance in the New Testament can be found in the parable of the prodigal son found in the Gospel of Luke (15 beginning at verse 11).
In the Hebrew Bible, repentance generally leads to salvation. In some cases, individuals or nations repent of their sins and are spared God's judgment. Sometimes the punishment avoided is destruction in this life, sometimes it is damnation. In the book of Jonah, the prophet initially chose to disobey God's command, and then he repented and became obedient. However, Jonah returned to disobedience when he hoped for the destruction of the city of Ninevah. In the Book of Job, Job never repented of any particular sin or activity when he went through his major dilemma. The Hebrew term teshuvah (lit. "return") is used to refer to "repentance". This implies that transgression and sin are the natural and inevitable consequence of man's straying from God and his laws , and that it is man's destiny and duty to be with God. The Hebrew Bible states that it is within man's power to redeem himself from sin by breaking away from it and turning to God. The Bible states that God's loving-kindness is extended to the returning sinner.
The Torah (five books of Moses) distinguishes between offenses against God and offenses against man. In the first case the manifestation of repentance consists in: (1) Confession of one's sin before God (Lev. 5:5; Num. 5:7), the essential part being a solemn promise and firm resolve not to commit the same sin again. (2) Making certain prescribed offerings (Lev. 5:1-20). Offenses against man require, in addition to confession and sacrifice, restitution in full of whatever has been wrongfully obtained or withheld from one's fellow man, with one-fifth of its value added thereto (Lev. 5:20-26). If the wronged man has died, restitution must be made to his heir; if he has no heir, it must be given to the priest who officiates at the sacrifice made for the remission of the sin (Num. 5:7-9).
There are other manifestations of repentance mentioned in the Bible. These include pouring out water, which symbolizes the pouring out of one's heart before God; prayer self-affliction, as fasting; wearing sackcloth; sitting and sleeping on the ground  However, the Prophets disparaged all such outer manifestations of repentance, insisting rather on a complete change of the sinner's mental and spiritual attitude.  In Isaiah 55:7, the Bible states that repentance brings pardon and forgiveness of sin. Apart from repentance, no other activities, such as sacrifices or religious ceremonies can secure pardon and forgiveness of sin.
Rabbinic Jewish literature contains extensive discussions on the subject of repentance. Many rabbinic sources state that repentance is of paramount importance to the existence of this world, so that it was one of the seven provisions which God made before the Creation (Talmud Bavli, tractates Pesahim 54a; Nedarim 39b; Midrash Genesis Rabbah 1). "The Holy One, blessed be His name, said to Elijah, 'Behold, the precious gift which I have bestowed on my world: though a man sins again and again, but returns in penitence, I will receive him'" (Jerusalem Talmud Sanhedrin 28b). "Great is repentance: it brings healing into the world"; "it reaches to the throne of God" (Hosea 14:2, 5); "it brings redemption" (Isiah 59:20); "it prolongs man's life" (Ezekiel 18:21; Talmud Yoma 86a). "Repentance and works of charity are man's intercessors before God's throne" (Talmud Shabbath 32a). Sincere repentance is equivalent to the rebuilding of the Temple, the restoration of the altar, and the offering of all the sacrifices .
Sincere repentance is manifested when the same temptation to sin, under the same conditions, is ever after resolutely resisted. "He that confesses his sin and still clings to it is likened to a man that holds in his hand a defiling object; though he batheth in all the waters of the world he is not cleansed; but the moment he casteth the defiling object from him a single bath will cleanse him, as it is said 'Whosoever confesses and forsakes them [his sins] shall have mercy'" .
According to Jewish doctrine, repentance is the prerequisite of atonement . Yom Kippur, the day of atonement, derives its significance only from the fact that it is the culmination of the ten penitential days with which the Jewish religious year begins; and therefore it is of no avail without repentance; (Midrash Sifra, Emor, 14.). Though man ought to be penitent every day (Mishna Avoth Chap 2, 10; Talmud Shabbath 153a), the first ten days of every year are the acceptable time announced by the prophet (Isiah 60:6): "Seek the Lord while he may be found, call upon him while he is near" (Talmud Rosh Hashan 18a; Mishneh Torah Teshuva 2:6). Repentance and the Day of Atonement only absolve one from sins committed against God; from sins against another person they absolve only when restitution has been made and the pardon of the offended party has been obtained (Talmud Yoma 87a; Mishneh Torah Teshuva2:9).
No one need despair on account of his or her sins, for every penitent sinner is graciously received by God. (Jeremiah 31:9). Jewish doctrine holds that it is never too late, even on the day of death, to return to God with sincere repentance for "as the sea is always open for every one who wishes to cleanse himself, so are the gates of repentance always open to the sinner" . Jewish doctrine states that the hand of God is continually stretched out to receive a sinner . One view in the Talmud holds that a repentant sinner attains a more exalted spiritual eminence than one who has never sinned (Talmud Berakhoth 34b.) It is a sin to taunt a repentant sinner by recalling their former sinful ways . Repentance occupies a prominent position in all the ethical writings of the Middle Ages. Bahya ibn Paquda devotes a special section to it in his 'Hovot ha-Levavot", "Gate of Repentance." Maimonides devotes the last section of "Sefer ha-Madda'" in his Mishneh Torah to the subject. One of the most significant medieval works on Repentance is "Shaarei Teshuva," the "Gates of Repentance" by Rabbeinu Yona of Gerona.
The doctrine of Repentance in the Scriptures appears to be very prominent. See the description of repentance in the Hebrew Bible above for repentance in the Old Testament. In the New Testament, John the Baptist began his public ministry, as did Jesus, with a call to repentance (Matthew 3:1–2; Matthew 4:17). In the Acts 2 sermon on Pentecost, Peter commands repentance. In the Acts 3 sermon at the Beautiful gate of the Temple, Peter interchanges the phrase "turn again" at a similar place in his presentation. When Jesus sent forth messengers to proclaim his gospel, he commanded them to preach repentance (Luke 24:47; Mark 6:12). Teachings on repentance are found in the New Testament in Peter, (Acts 2:38); Paul, (Acts 20:21). God wants everyone to repent (2 Pet. 3:9; Acts 17:30). Indeed, failure on the part of man to heed God's call to repentance means that he shall utterly perish (Luke 13:3).
The constant references to repentance in Peter's preaching to his fellow countrymen in the early part of the book of Acts may indicate an exceptional need for repentance amongst those who had recently been party to the crucifixion of Christ. Paul is emphatic that change take place amongst those who he taught (see the Bible references to "turning to a true and living God"). This aversion to the Greek or idolatrous lifestyle may have come from the intense patriotism to Jewish ideals held by the well educated former Pharisee . Saint Isaac of Syria said, "This life has been given to you for repentance. Do not waste it on vain pursuits."
There is a three-fold idea involved in true repentance in the Protestant conception. The Protestant reformer John Calvin said that repentance "may be justly defined to be “a true conversion of our life to God, proceeding from a serious fear of God, and consisting in the mortification of the flesh and of the old man, and in the vivification of the Spirit.” He further said that "it will be useful to amplify and explain the definition we have given; in which there are three points to be particularly considered." "In the first place, when we call repentance “a conversion of the life to God, we require a transformation, not only in the external actions, but in the soul itself; which, after having put off the old nature, should produce the fruits of actions corresponding to its renovation. . . .In the second place, we represented repentance as proceeding from a serious fear of God. For before the mind of a sinner can be inclined to repentance, it must be excited by the knowledge of the Divine judgment.
"It remains for us, in the third place, to explain our position, that repentance consists of two parts—the mortification of the flesh and the vivification of the spirit. . . . Both these branches of repentance effects our participation of Christ. For if we truly partake of his death, our old man is crucified by its power, and the body of sin expires, so that the corruption of our former nature loses all its vigor. . . .If we are partakers of his resurrection, we are raised by it to a newness of life, which corresponds with the righteousness of God." [Quotes from A Compend of the Institutes of the Christian Religion by John Calvin edited by Hugh T. Kerr, The Westminster Press-Philadelphia 1939.]
Matthew 21:29: "He answered and said: I will not; but afterward he repented, and went". The word here used for "repent" means to change one's mind, thought, purpose, views regarding a matter; it is to have another mind about a thing. This change is well illustrated in the action of the Prodigal Son, and of the Publican in the well-known story of the Pharisee and the Publican (Luke 15 and 18). 2 Cor. 7:9--"Now I rejoice, not that ye were made sorry, but that ye sorrowed to repentance; for ye were made sorry after a godly manner, that ye might receive damage by us in nothing." See also Luke 10:13; cf. Gen. 6:6. The Greek word for repentance in this connection means "to be a care to one afterwards," to cause one great concern. This meaning is exemplified by the repentant person who not only has profound regret for his past but also the fulfilled hope in the potential of God’s grace to continually bear the fruit of healing and true reconciliation in himself, with others, and most especially with God. The Hebrew equivalent is strong as well, and it means to pant, to sigh, or to moan. So the publican "beat upon his breast," indicating sorrow of heart. See also Psalms 38:18.
The issue of repentance is also discussed in connection with the will and disposition. One of the Hebrew words for repent means "to turn." The Prodigal Son said, "I will arise... and he arose" (Luke 15:18, 20). The part of the will and disposition in repentance is shown in the Confession of sin to God: Psa. 38:18 -- "For I will declare mine iniquity: I will be sorry for my sin." The publican beat upon his breast, and said, "God be merciful to me a sinner" (Luke 18:13). The prodigal said, "I have sinned against heaven" (Luke 15:21). There must be confession to man also in so far as man has been wronged in and by our sin (Matthew 5:23–24); James 5:16). Isa. 55:7 Prov. 28:13 ("He that covereth his sins shall not prosper: but whoso confesseth and forsaketh them shall have mercy."); Matthew 3:8–10 ("Bring forth therefore fruits meet for repentance:... And now also the axe is laid unto the root of the trees: therefore every tree which bringeth not forth good fruit is hewn down, and cast into the fire."). It is not enough to turn away from sin; we must turn unto God. 1 Thessalonians 1:9; Acts 26:18.
According to Christians, acts of repentance do not earn God's forgiveness from one's sin; rather, forgiveness is given as a gift from God to those who he saves. Acts 11:18--"Then hath God also to the Gentiles granted repentance unto life." 2 Tim. 2:25 -- "If God peradventure will give them repentance to the acknowledging of the truth." Acts 5:30, 31. In this view, people are called upon to repent in order that we may feel our own inability to do so, and consequently be thrown upon God and petition Him to perform this work of grace in our hearts. Many church fathers have made reference to it as the "gift of repentance" or as the "gift of tears". God calls all to repent through the hearing of the Gospel. God grants total repentance as each individual responds to repentance through faith in the expiating sacrifice of Jesus for all sin. "So then faith cometh by hearing, and hearing by the word of God." (Romans 10:17). Repentance is given before anything else by definition. One cannot show true change in his life before he himself has changed [repented] to bring about manifestations of that change/repentance.
Acts 2:37, 38, 41. The very Gospel which calls for repentance produces it. When the people of Nineveh (Jonah 3:5-10) heard the preaching of the word of God by Jonah they believed the message and turned unto God. Not any message, but the Gospel is the instrument that God uses to bring about this desired end. Furthermore, this message must be preached in the power of the Holy Spirit (1 Thess. 1:5-10). Rev. 3:19; Heb. 12:6, 10-11. The chastisements of God are sometimes for the purpose of bringing His wandering children back to repentance. 2 Tim. 2:24-25. God often uses the loving, Christian reproof of a brother to be the means of bringing us back to God.
The word “Tawbah” (Repentance) in Arabic literally means 'to return', and is mentioned in the Qur'an. In an Islamic context, it refers to the act of leaving what Allah Has prohibited and returning to what He Has Commanded.
Repentance means that a person wants to get rid of the sin that it has committed. In some cases, individuals or nations repent of their sins and are spared God's judgment. Sometimes the punishment avoided is destruction in this life, sometimes it is damnation.
If repentance is successful one speaks of salvation.