Most people are aware of the famous vision seen by Constantine the Great of a cross in the sky with the words, "In hoc signo, vinces" — by this sign you will conquer. Having seen this miraculous vision, Constantine would cause his soldiers to march under Christian symbols, be victorious in his wars, and eventually convert to Christianity. Many citizens of the Roman Empire would follow him. But not all. During the reign of Constantine's sons, paganism continued to be practiced throughout the empire. Indeed, thanks to the weak rule and the rumored personal scandals of Constans, a pagan usurper...