Empire to Commonwealth: Consequences of Monotheism in Late Antiquity - Paperbackby Garth Fowden (Author) In this bold approach to late antiquity, Garth Fowden shows how, from the second century peak of Rome's prosperity to the ninth century onset of the Islamic Empire's decline, powerful beliefs in One God were used to justify and strengthen "world empires." But tensions between orthodoxy and heresy that were inherent in monotheism broke the unitary empires of Byzantium and Baghdad into the looser, more pluralistic commonwealths