Over the course of the fourth century, Christianity rose from a religion actively persecuted by the authority of the Roman empire to become the religion of state--a feat largely credited to Constantine the Great. Constantine succeeded in propelling this minority religion to imperial status using the traditional tools of governance, yet his proclamation of his new religious orientation was by no means unambiguous. His coins and inscriptions, public monuments, and pronouncements sent unmistakable signals to his non-Christian subjects that he was willing not only to accept their beliefs about...