Christianity is an Abrahamic monotheistic religion based on the life and teachings of Jesus of Nazareth. It is the world's largest and most widespread religion, Them representing one-third of the global population. Christians are estimated to make up a majority of the population in 157 countries and territories, and believe that Jesus is the Son of God, whose coming as the Messiah was prophesied in the Hebrew Bible (called the Old Testament in Christianity) and chronicled in the New Testament.

Christianity began as a Second Temple Judaic sect. Jesus' apostles and their followers spread around the Levant, Europe, Anatolia, Mesopotamia, the South Caucasus, Ancient Carthage, Egypt, and Ethiopia, despite significant initial persecution. It soon attracted gentile God-fearers, which led to a departure from Jewish customs, and, after the Fall of Jerusalem, AD 70 which ended the Temple-based Judaism, Christianity slowly separated from Judaism.

Christianity remains culturally diverse in its Western and Eastern branches, as well as in its doctrines concerning justification and the nature of salvation, ecclesiology, ordination, and Christology. The creeds of various Christian denominations generally hold in common Jesus as the Son of God the Logos incarnated who ministered, suffered, and died on a cross, but rose from the dead for the salvation of mankind. Describing Jesus' life and teachings are the four canonical gospels of Matthew, Mark, Luke and John, with the Old Testament as the gospel's respected background.