The three Abrahamic religions, Judaism, Christianity, and Islam, are often referred to as "religions of the book" because their religious beliefs include reliance on scriptural texts as sources of religious authority; in the most extreme form, this reliance on scripture becomes the "sola scriptura", or salvation by scripture alone, doctrine of some branches of Christianity.
All three Abrahamic religions accept the majority of the Hebrew Old Testament as a religious text. Where they diverge is that most branches of Judaism accept only the Old Testament and commentaries on it as containing religious truth, and believe that the Messiah predicted in the Old Testament has yet to arrive. Christians identify Jesus Christ with the Jewish Messiah, and accept as Scripture the New Testament accounts of Jesus and his followers as well. Islam accepts Jesus and the Jewish prophets, and the Bible as an edifying text, but believes Mohammed to have been the final religious prophet and the Koran given to Mohammed as the final and authoritative scriptural text.