Manichaeism, once the state religion of Persia and long a vigorous contender for converts throughout the ancient Near East, is best remembered for the simplicity of its teachings about divine power. For Manicheans, the universe was ruled by a Lord of Light and a Lord of Darkness, who fought continuously for supremacy. All that was good was a gift from the Lord of Light, and all that was evil was an affliction visited by the Lord of Darkness. This dualism extended to cosmogony and ethics, splitting the universe into a spiritual realm that acted on the goodness of the human soul and a...