5 September 394 A.D. A major battle and victory went to Emperor Theodosius I, otherwise known as “Theodosius the Great”
Christianizing features in the Roman Empire began with Constantine the Great. “In this sign, conquer” became a well-known phrase from his time. He favored Christianity and promoted it. The Roman bureaucracy was full of non-Christian pagans. The Christian majority was in the East: Asian, Bythynia, Pontus, parts of Armenia, and North Africa. Constantine’s successors continued the policy of favoring Christians until Julian the Apostate ascended the throne.
Julian the Apostate sought to restore pagan religion and culture. But, he died and Emperor Gratian assumed the throne, adopting a program “more ruthless in the treatment of paganism” (498). Gratian refused the title Pontifex Maximus (senior priest of the Roman religion, essentially, an all-inclusive set of pluralistic deities). Further, he cut off subsidies for the Roman cults. Things were looking down for the old religionists.
Theodosius I became the Emperor of the eastern portion of the Roman Empire, based in Constantinople. His was another “ruthless brand of Christianity” (499). At the prompting of Milan’s bishop, St. Ambrose, he “passed harsh laws making it treason to offer any kind of sacrifice, removing all idols, and fining anybody who visited a pagan temple.”
By the way, Mr. (Bp) Ambrose would also chastise and refuse communion to Theodosius without public repentance after Mr. Theodosius slaughtered 100s of Corinthians in Macedonia, but that’s an aside.
Paganism, like all cherished worldviews, was not going away easily. In 392, Eugenius (a supposed Christian), ascended to the throne in Rome. He rode off to battle with the eastern Emperor, Theodosius.
The two sides engaged in battle at the Frigidus River, south of the Alps. Eugenius’ troops had their battle banners unfurled with “Hercules” as their patron-deity. Theodosius’ forces won on 5 September 394 A.D.