Christianity is an Abrahamic, monotheistic religion based on the life and teachings of Jesus of Nazareth. It is the world's largest religion, with about 2.4 billion followers.Its adherents, known as Christians, make up a majority of the population in 157 countries and territories, and believe that Jesus is the Christ, whose coming as the Messiah was prophesied in the Hebrew Bible (called the Old Testament in Christianity) and chronicled in the New Testament.