This is coolbert:
Here with a high-water historical event I was not familiar with. Thanks to the tip from Steve.
Frigidus. The military forces of western Rome and eastern Rome in conflict. The former favoring what can best be described as neo-paganism. The latter definitely representative of Christianity.
"The Battle of the Frigidus, also called the Battle of the Frigid River, was fought between September 5–6 394, between the army of the Eastern Emperor Theodosius I and the army of Western Roman ruler Eugenius."
"Because the Western Emperor Eugenius (though nominally Christian) had pagan sympathies, the war assumed religious overtones, with Christianity pitted against the last attempt at a pagan revival. The battle was the last serious attempt to contest the Christianization of the empire; its outcome decided the outcome of Christianity in the western Empire, and the final decline of Greco-Roman polytheism in favour of Christianity over the following century."
From the defeat of Eugenius forward the European cultural domain decidedly Christian. The ancient gods defunct and no longer worthy of worship. Constantine having made Christianity the official religion of Rome in the previous century, understand that significant numbers of persons in the realm still loyal and paying homage to the pagan gods.
Understand too and appreciate that for almost a thousand years beyond some national and tribal groups in Europe remained pagan, the people of the Baltic area the last to be receive baptism.