Christianity is a monotheistic religion based on the life and teachings of Jesus as found in the books of the New Testament. Followers of Christianity believe that Jesus was the son of God, and that he offered salvation to humanity through his death by crucifixion and subsequent resurrection in the first century C.E. Christians believe that Jesus is the Messiah prophesied in the books of the Hebrew Bible, incorporated into Christian scripture as the "Old Testament." The Old and New Testaments together are referred to collectively as the Christian Bible. A series of historical schisms created the many divisions in Christianity today, including the Eastern Orthodox Churches, the Roman Catholic Church and the many Protestant denominations. Based on global population, Christianity is the largest religion in the world, with upwards of 2.2 billion adherents.