Christianity originated from the teachings of Jesus Christ. Key beliefs include that Jesus was the son of God, was resurrected after being crucified, and sacrificed himself to save humanity from sin. The Christian Bible consists of the Old and New Testaments. Symbols of Christianity include the ichthys symbol, the Holy Trinity, and the Alpha and Omega symbols. Churches share common features like crosses but vary in style, size, and traditions. Rites of passage include communion, baptism, and confirmation. Major holidays are Lent, Easter, Christmas, and Holy Week. Christianity spread rapidly after Jesus' death and Paul's missionary work, becoming the world's largest religion by the 4th century CE.