In the generation after Constantine the Great elevated Christianity to a dominant position in the Roman Empire, his nephew, the Emperor Julian, sought to reinstate the old gods to their former place of prominence—in the face of intense opposition from the newly powerful Christian church. In early 363 c.e., while living in Syrian Antioch, Julian redoubled his efforts to hellenize the Roman Empire by turning to an unlikely source: the Jews. With a war against Persia on the horizon,...