Religious beliefs and practices of the Jews. One of the three great monotheistic world religions, Judaism began as the faith of the ancient Hebrews, and its sacred text is the Hebrew Bible, particularly the Torah. Fundamental to Judaism is the belief that the people of Israel are God's chosen people, who must serve as a light for other nations. God made a covenant first with Abraham and then renewed it with Isaac, Jacob, and Moses. The worship of Yahweh (God) was centred in Jerusalem from the time of David. The destruction of the First Temple of Jerusalem by the Babylonians (586 BCE) and the subsequent exile of the Jews led to hopes for national restoration under the leadership of a messiah. The Jews were later allowed to return by the Persians, but an unsuccessful rebellion against Roman rule led to the destruction of the Second Temple in 70 CE and the Jews' dispersal throughout the world in the Jewish Diaspora. Rabbinic Judaism emerged to replace the beliefs and practices associated with the Temple at Jerusalem, as the Jews carried on their culture and religion through a tradition of scholarship and strict observance. The great body of oral law and commentaries were committed to writing in the Talmud and Mishna. The religion was maintained despite severe persecutions by many nations.
Two branches of Judaism emerged in the Middle Ages: the Sephardic, centred in Spain and culturally linked with the Babylonian Jews; and the Ashkenazic, centred in France and Germany and linked with the Jewish culture of Palestine and Rome. Elements of mysticism also appeared, notably the esoteric writings of the Kabbala and, in the 18th century, the movement known as Hasidism. The 18th century was also the time of the Jewish Enlightenment (Haskala). Conservative and Reform Judaism emerged in 19th-century Germany as an effort to modify the strictness of Orthodox Judaism. By the end of the 19th century Zionism had appeared as an outgrowth of reform. European Judaism suffered terribly during the Holocaust, when millions were put to death by the Nazis, and the rising flow of Jewish emigrants to Palestine led to the declaration of the State of Israel in 1948. In the early 21st century there were nearly 15 million Jews worldwide.