Many theologians have argued that the Jewish theology of love is centered on justice, as opposed to the Christian conception of charity.
As in English, the Hebrew word for "love," ahavah אהבה, is used to describe intimate or romantic feelings or relationships, such as the love between parent and child in Genesis 22:2; 25: 28; 37:3; the love between close friends in I Samuel 18:2, 20:17; or the love between a young man and young woman in Song of Songs. Other related but dissimilar terms are [chen] (grace) and chesed, which basically combines the meaning of "affection" and "compassion" and is sometimes rendered in English as "loving-kindness".
Like many Jewish scholars and theologians, Bloom understands Judaism as fundamentally a religion of love. But he argues that one can understand the Hebrew conception of love only by looking at one of the core commandments of Judaism, Leviticus 19:18, "Love your neighbor as yourself", also called the Great Commandment. Talmudic sages Hillel and Rabbi Akiva commented that this is a major element of the Jewish religion. Also, this commandment is arguably at the center of the Jewish faith. As the third book of the Torah, Leviticus is literally the central book. Historically, Jews have considered it of central importance: traditionally, children began their study of the Torah with Leviticus, and the midrashic literature on Leviticus is among the longest and most detailed of midrashic literature . Bernard Bamberger considers Leviticus 19, beginning with God's commandment in verse 3 – "You shall be holy, for I the Lord your God, am holy" – to be "the climactic chapter of the book, the one most often read and quoted" . Leviticus 19:18 is itself the climax of this chapter.
The commandment to love one's neighbor itself arises out of another unique love: the relationship between God and the Children of Israel. That the relationship between God and the Children of Israel is a romantic relationship and comparable to the marital bond is made clear in Hosea 2:19 (see also Ezekiel 16:8, 60; Isaiah 54:5; Jeremiah 3:14; 31:32). The centrality of love to the relationship between God and Israel is epitomized in Deuteronomy 6: 4-5: "Hear O Israel, the Lord is our God; the Lord is one. You shall love the Lord your God with all your heart, with all your soul, and with all your might." Arguably, this commandment, the Shema, is as central to Judaism as Leviticus 19: 18, as it was recited twice daily in the Temple in Jerusalem, and in the prayers of all observant Jews. Moreover, the Rabbis dictated that all Jews should recite this verse at the moment of their death (this custom contrasts with Mathew 27: 46, "About the ninth hour Jesus cried out in a loud voice, 'Eloi, Eloi, lama sabachthani?' — which means, "My God, my God, why have you forsaken me?" see also Mark 15: 33; Luke 23: 46, however, is closer to the spirit of Jewish practice: "Jesus called out with a loud voice, 'Father, into your hands I commit my spirit.' When he had said this, he breathed his last.")
The Torah states: "Love your neighbour like yourself" (Leviticus 19:18). As for the latter, one is commanded to love God "with all your heart, with all your soul and with all your might" (Deuteronomy 6:5), taken by the Mishnah (a central text of the Jewish oral law) to refer to good deeds, willingness to sacrifice one's life rather than commit certain serious transgressions, willingness to sacrifice all one's possessions and being grateful to the Lord despite adversity (tractate Berachoth 9:5, tractate Sanhedrin 74a). Rabbinic literature differs how this love can be developed, e.g. by contemplating Divine deeds or witnessing the marvels of nature (Maimonides, Mishneh Torah, Hilchot Yesoday HaTorah, Chapter 2).
Apparently by the Hellenistic period these two commandments were understood to be central to Jewish faith. These two commandments to love are inextricably connected, but in a complex way. He finds it remarkable that throughout the Pentateuch it is demanded that Israel love God, yet never professes love for Israel (except in the future; that if Israel loves God they will be blessed in return). But he does not see this as evidence that God does not love Israel; on the contrary. Rosenzweig asks, how can someone command love? The only answer, he argues, is that only a lover can do so; only one who loves can demand, "love me!' in return . The consequences of this demand provide the foundation for Judaism.
The first consequence of being loved is a feeling of shame:
Thus, the immediate response to God's commandment to love is to confess, "I have sinned." For Rosenzweig this confession is not a source of shame; on the contrary, by speaking a truth about the past, it makes love in the present possible and thus "abolishes shame."
Consequently, Jewish writers have said that confession does not require absolution:
In other words, the Hebrew Bible is seen a "grammar of love" in which God can communicate "I love you" only by demanding "You must love me," and Israel can communicate "I love you" only by confessing "I have sinned." Therefore, this confession does not lead God to offer an unnecessary absolution; it merely expresses Israel's love for God.
But "What then is God's answer to this 'I am thine' by which the beloved soul acknowledges him" if it is not "absolution?" Rosenzweig's answer is: revelation: "He cannot make himself known to the soul before the soul has acknowledged him. But now he must do so. For this it is by which revelation first reaches completion. In its groundless presentness, revelation must now permanently touch the ground."  Revelation, epitomized by Sinai, is God's response to Israel's love. Contrary to Paul, who argued that "through the law comes knowledge of sin" , Rosenzweig argues that it is because of and after a confession of sin that God reveals to Israel knowledge of the law.
As for love between marital partners, this is deemed an essential ingredient to life: "See life with the wife you love" (Ecclesiastes 9:9). The Biblical book Song of Songs is a considered a romantically-phrased metaphor of love between God and his people, but in its plain reading reads like a love song.
For the rabbis, Song of Songs provides a paradigm for understanding the love between God and Israel, a love that "is strong as death" . God's love is as strong as death because it is love for the People Israel, and it is as a collective that Israel returns God's love. Thus, although one may die, God and Israel, and the love between them, lives on. In other words, Song of Songs is "the focal book of revelation"  where the "grammar of love" is most clearly expressed. But , this love that is as strong as death ultimately transcends itself, as it takes the form of God's law — for it is the law that binds Israel as a people, and through observance of the law that each Jew relives the moment of revelation at Mt. Sinai. Ultimately, Song of Songs points back to Leviticus and the rest of the Torah.
Song of Songs largely describes a clandestine love affair, forbidden by the woman's brothers , and scorned by her friends . The concealed nature of this romance is emblematic of the way lovers lose themselves in one another. Yet the book itself struggles against this private love. "O that you were like a brother to me," the woman cries, "that nursed at my mother's breast! If I met you outside, I would kiss you, and none would despise me" . The point, is that love neither can nor should remain private.
Whereas Jews believe that law is the ultimate fulfillment of love, Christians believe that love is "the fulfillment of the Law". For Rosenzweig, as for the Rabbis, it cannot be fulfilled in love, it can be fulfilled only in law. This is the meaning of revelation: Israel's love provides God with the means to enter the world, and through the commandments to Israel their love enters "the street." It is through the revelation of God's commandments, according to Rosenzweig, that the love portrayed in Song of Songs becomes the love commanded in Leviticus. Just as love for the Children of Israel is one of the ways that God is present in the world, the necessary response by the Jews — the way to love God in return — is to extend their own love out towards their fellow human beings.
The lover has explained his love for her .... But will this explanation do? Does not life demand more than explanation, more than the calling by name? Does it not demand reality? And a sob escapes the blissfully overflowing heart of the beloved and forms into words, words which haltingly point to something unfulfilled, something which cannot be fulfilled in the immediate revelation of love: "O that you were like a brother to me!" Not enough that the beloved lover calls his bride by the name of sister in the flickering twilight of allusion. The name ought to be the truth. It should be heard in the bright light of "the street," not whispered into the beloved ear in the dusk of intimate duo-solitude, but in the eyes of the multitude, officially — "who would grant" that! Yes, who would grant that? Love no longer grants it. In truth, this "who would grant" is no longer directed to the beloved lover. Love after all always remains between two people; it knows only of I and Thou, not the street. 
This extension of God's love into the world, through the People Israel, is the point of Leviticus 19:18. According to Bloom, however, this love has a different character than the romantic love celebrated in Song of Songs. He argues that to understand the commandment to love one's neighbor one must look at the other commandments that form its context, beginning with verse 9:
According to Bloom these accompanying commandments reveal that for Israel, love "in the street" takes the form of "just dealing." Similarly, theologian William Herberg argued that "justice" is at the heart of the Jewish notion of love, and the foundation for Jewish law:
The arguments of Rosenzweig, Herberg, and Bloom echo the teachings of the Rabbis, who taught that the written and oral Torahs provide the way to express this love-as-just-dealing. This view is encapsulated in one of the most famous rabbinic stories, that of the time a man once challenged Hillel the Elder, an important Pharisee who lived at the end of the 1st century BCE, to explain the entire law (Torah) while standing on one foot.
Hillel replied, "That which is hateful to you, do not do to your friend. That is the whole Torah; the rest is the explanation -- go and study it." Hillel presented the commandment from Leviticus in the negative form (do not do it) as a way of setting up his own, affirmative, commandment: to go and study the law — in other words, the only way to fulfil Leviticus 19:18 is to observe all the laws of the Torah, the practical embodiment of the commandment to love.
Similarly, Maimonides wrote that it should only be out of love for God, rather than fear of punishment or hope for reward, that Jews should obey the law: "When man loves God with a love that is fitting he automatically carries out all the precepts of love" .
The 20th-century rabbi Eliyahu Eliezer Dessler is frequently quoted as defining love from the Jewish point-of-view as "giving without expecting to take" (from his Michtav me-Eliyahu, vol. I). Romantic love per se has few echoes in Jewish literature, although the medieval rabbi Judah Halevi wrote romantic poetry in Arabic in his younger years (he appears to have regretted this later).
As theologian Franz Rosenzweig has pointed out, "love" in this context is remarkably different from the more common examples of love in that it constitutes an impersonal relationship:
(This point is underscored by another verse in the same chapter, Leviticus 19: 34, commanding the Children of Israel to love strangers.)
Bloom argues that the Hebrew word for love, ahavah אהבה , is fundamentally understood as "just dealing."