Judaism, religious culture of the Jews, one of the world's oldest religious traditions. Premodern Judaism constituted (and traditional Judaism today constitutes) an integrated cultural system of Jewish law, custom, and practice encompassing the totality of individual and communal existence. It is a system of sanctification in which all is to be subsumed under God's rule. Judaism originated in the Middle East, but Jewish communities have existed at one time or another in almost all parts of the world, a result of both voluntary migrations and forced exile or expulsions. In the early 1990s the total world Jewish population was about 12.8 million, most of whom lived in the United States, Israel, and the former Union of Soviet Socialist Republics.

The various historical forms of Judaism have shared certain characteristic features. The most essential of these is a belief that a single, transcendent God created the universe and continues providentially to govern it. The same God who created the world revealed himself to the Israelites at Mount Sinai. The content of that revelation is the Torah ("revealed instruction"), God's will for humankind expressed in commandments. A second major concept in Judaism is that of the covenant, or contractual agreement, between God and the Jewish people. They would acknowledge God, agreeing to obey his laws; God, in turn, would acknowledge Israel as his particular people. Both natural and historical events that befall Israel are interpreted as emanating from God and as influenced by Israel's religious behavior. Much Jewish religious thought has been preoccupied with the problem of affirming justice and meaning in the face of apparent injustice. In time, the problem was mitigated by the belief that virtue and obedience ultimately would be rewarded and sin punished by divine judgment after death, and that at the end of time God would send his Messiah to redeem the Jews and restore them to sovereignty in their land.

Although all forms of Judaism have been rooted in the Hebrew Bible, contemporary Judaism is ultimately derived from the rabbinic movement of the first centuries of the Christian era in Palestine and Babylonia. In Palestine at the turn of the 3rd century, the rabbis, or Jewish sages, produced the Mishnah, the earliest document of rabbinic literature. Subsequent study of the Mishnah generated two Talmuds, wide-ranging commentaries on the Mishnah. The study of Torah refers to the study of all this literature.

Traditionally, Jews pray three times a day. A company of ten men forms a congregation for prayer. The study of Torah, the revealed will of God, also is considered an act of worship in rabbinic Judaism. The Torah is read liturgically each Sabbath, the seventh day of the week, which is spent in prayer, study, rest, and family feasting; in the course of a year, the entire Torah will be read on Sabbath and festival days. The Jewish year includes five major festivals— Passover, Shabuoth, Sukkot, Rosh Hashanah, and Yom Kippur— and two minor ones— Hanukkah and Purim.

Although worshipping only one God themselves, the earliest Israelites did not deny the existence of other gods for other nations. Preexilic Israel, first as a confederation of tribes and then as a kingdom, celebrated as its formative experiences the redemption from Egyptian bondage and, particularly, the conquest and settlement of the land of Canaan (the land of Israel). Its deity was Yahweh (see Jehovah), the god of the patriarchs, who was worshipped in a sacrificial cult centered in Jerusalem and later at sanctuaries in the north, where a rival Jewish kingdom was formed.

The Arab conquest of the Middle East in the 600s facilitated the spread of a uniform rabbinic Judaism. The heads of the Babylonian rabbinical academies attempted to standardize Jewish law, custom, and liturgy. Rabbinic intellectuals cultivated philosophy to defend Judaism against Islamic theologians and to demonstrate to other Jews the rationality of their revealed faith and law. Throughout the medieval period, Judaism was continually revitalized by mystical and ethical-pietistic movements. The most significant of these were the 12th-century German Hasidic, or "pietist," movement and the 13th-century Spanish Cabala, an esoteric theosophy.

The civil emancipation of European Jewry in the 1700s evoked different reformulations of Judaism in western and eastern Europe. In the west, Judaism was reformulated as a religious confession like modern Protestantism. In eastern Europe, modernization took the form of cultural and ethnic nationalism, which gave birth to Zionism, the movement to create a modern Jewish society in the ancient homeland.