In the Shadow of the Sword: The Birth of Islam and the Rise of the Global Arab Empire

Debates about the relationship between God the Father and God the Son convulsed the Christian world for centuries. This mosaic, illustrating the baptism of Jesus, was commissioned by a follower of Arius, who taught that the Father had preceded the Son. The doctrine was condemned as heretical at the great Church Council of Nicaea, summoned by Constantine in 325. (Giraudon/Bridgeman Art Library)