Judaism, religion of the Jewish people, the oldest of the world's monotheistic faiths. The essence of Judaism is the belief in one God. At daily prayers and services Jews repeat the words of Deuteronomy 6:4: “Hear O Israel: The Lord our God, the Lord is One.” In Jewish beliefs, Abraham, the Jewish patriarch, made a covenant with God that he and his descendants would carry the message of the one God. This covenant, the burden of special service to God, is Judaism's reason for being, and the relationship between God and the Chosen People is the subject of the Hebrew Bible, the foundation of Judaism. The Torah, the first part of the Bible (known as the Five Books of Moses, or the Pentateuch), contains the Ten Commandments and the ritual laws and ethical precepts that form the structure of the Jewish religion. In the centuries after the Bible was completed, its text was explained and adapted by a set of traditions and interpretations known as the Oral Law. When the Temple of Jerusalem and the hereditary priesthood were destroyed in A.D. 70, the Oral Law was recorded in a work known as the Mishnah, the discussion and interpretation of which forms a commentary called the Gemara. These two works together make up the Talmud, second only to the Bible in its authority. Differences over ritual observance are the chief characteristics of the groups within Judaism today. Reform Judaism began in the 19th century in answer to the challenge of rationalism. Reform Jews believe that each generation has the right to adapt or discard traditions it finds no longer meaningful. Much of the Reform synagogue service in the United States is in English, and the compatibility of Judaism with modern secular values is emphasized. Orthodox Judaism accepts the totality of the Bible and the Oral Law as divine revelation and holds strictly to all dietary laws and codes of conduct. Religious services are conducted solely in Hebrew, men and women sitting in separate parts of the synagogue. The extremes of Reform and Orthodox Judaism have to some extent been bridged in the United States by the Conservative movement, which has attempted to combine the traditions of Orthodox observance with some of the freedom of choice and adaptability found in Reform Judaism.