After the conversion of Constantine I to Christianism and the Edict of Milan, how fast was the actual conversion of the empire to Christianism?
I mean, in the more remote provinces like Lusitania in the west or Armenia in the east, was it felt in a short span of time, or was there resistance to change from the local rulers and it ended up being more of a theoretical thing than actually happening for the (previously) prosecuted Christians there?
There are varying numbers given, but Rodney Stark's The Rise of Christianity says that the rate of growth from 100 to 300 was about 43% per decade (or 3.42% growth per year). He's basing this off of a few things, one of which is the rate of growth for the Latter-Day Saints (i.e. Mormons). So by the year 300, something like 6.3 million people were Christians (about 10% of the overall population of the Empire). Constantine's conversion should be seen, says Stark, as part of the growing influence of Christianity in the Empire, not its cause. Already in the time of Galerius we see a change in Imperial policy when Galerius asks the Christians to pray to their own God for the safety of the Empire. By the mid-4th century, some Christian authors were speaking as though they were a majority. Thus Stark give a post-Constantinian estimate of 33.8 million Christians (roughly 56% of the population) in 350.