When Jesus became God: The struggle to define Christianity during the last days of Rome - Richard E. Rubenstein

After almost three hundred years of persecution, Christianity made an astonishing breakthrough in 324, when Constantine the Great became the emperor of Rome. No longer fearing for their own survival, Christians turned to the question of how to define what beliefs identified a "true" Christian. Led by two charismatic priests—Arius who preached that Jesus, though uniquely holy, is less than God, and Athanasius who argued that Jesus is God himself in human form—the debate over Jesus' degree of divinity escalated from heated argument to violence and bloodshed.

With vivid detail and meticulous research, Rubenstein re-creates the political intrigue, riots, and power struggles of one of the most critical moments in history—one with startling parallels to our own time.