As with most major shifts in policy or doctrine, it happened slowly, but I think we can isolate a couple of key moments, the first of which featuring Constantine the Great.
In 312, as Constantine was fighting to take control of the whole empire, which had essentially been divided into four parts by Diocletian in an effort to end the succession battles that had been taking place, he purportedly saw a vision in the sky of the Chi Rho monogram, a combination of the first two letters in the Greek word for Christ that was popular with Christians at the time, followed the next day by an appearance from Jesus himself in a dream. Inspired to emblazen the Chi Rho on the shields of his army, Constantine in 313 issued the Edict of Milan, extending freedom of religion to “Christians and all others.” In 324, upon taking the reins of both the eastern and western halves of the empire, Constantine extended the edict to everyone.
Constantine’s relationship to Christianity has always been disputed. The church historian Eusebius portrays Constantine as a great Christ-follower, but the fact is he wasn’t baptized until he was on his deathbed, and his official edicts tended not to favor Christianity so much as religious expression in general. As Ferguson in Church History Vol. 1 notes, “Constantine showed favor to Christians in various ways, but many of his actions were designed not to offend pagans or were subject to ambiguous interpretation.” Constantine did become the first emperor to insert himself into church affairs, calling the Council of Nicaea IN 325 to resolve the controversy over the teachings of the popular Alexandrian teacher Arius, who argued God and Jesus did not possess equal eternity – “there was when Christ was not” being his catchphrase, of sorts.
I get the sense Christians generally have given Constantine the cold shoulder, in part because of the mistaken perception that he required everyone to convert to Christianity – or at least made it so profitable to become a Christian that it watered down the true faith with thousands of “adherents” who didn’t actually care much for Jesus or his teachings.
But Constantine didn’t actually do that. His successor Theodosius did. In 380, Theodosius I declared the faith of the bishops of Rome and Alexandria to be the faith of the Roman Empire.
As an aside, that’s quite a turnaround. Christians were actively persecuted by the empire as recently as 311, yet 69 years later Christianity was the official religion. Compare this to the roughly 55-year shift between actively segregating African-Americans and electing one to be president of the United States. Things move much faster today than they did in antiquity; the official acceptance of Christianity by Rome occurred very, very quickly.
Anyway, this acceptance meant the principally stated reason for barring soldiers from the church collapsed. No longer were soldiers potentially being asked to arrest, torture and kill Christians. In fact, soldiers now fought with a Christian symbol on their shields.
The other major development in this era was the doctrine of sacraments established by Augustine, the famous bishop of Hippo, in what would become modern-day Algeria. Augustine as a NorthAfrican Catholic had to deal with the fact that he was a minority; most Christians were members of the Donatist church, which had split from Catholicism in the mid 310s over a number of rather mundane political issues about who should be bishop and how to venerate martyrs. Constantine called the Council of Arles to resolve the dispute in 314; among other things, the council forbade Christians from rejecting military service in peacetime and ruled against the Donatists.
Nevertheless, the Donatist church became quite the force in North Africa. Donatists were rigorists, which meant they took a hard line against those Christians who had rejected the faith in the Great Persecution of Diocletian from 303-11. More relevant, they argued baptism was effective only if the priest administering it had been properly ordained and was in good standing with God. So Catholics accepted Donatist baptism as a legitimate Christian baptism, even though they disagreed with Donatist positions that were less central to the basic faith, but the Donatists rebaptized Catholics who joined their church.
As he argued with the Donatists over this latter position, Augustine developed the doctrine of ex operate operatum – “it is worked by the work.” That is to say, the sacrament of baptism works regardless of who performs it because the baptism itself is doing the saving work, not the priest. This makes a lot of sense, I think. Is God really going to condemn someone because she was baptized by a priest who turned out to be ordained by some alleged heretic 20 years earlier?
But, like many of Augustine’s doctrines, this led to some unintended consequences, which we’ll discuss next week.