What if Constantine didn't convert to Christianity? Let's say that he does well like in OTL, but instead of becoming a full fledged convert, he concedes to simply not prosecuting the CHrsitians. So they don't have Rome on their case anymore, but neither do the Chrsitians have official sanction either. Does it spread as far and as wide still as in OTL, or does it become just another competing relgion of the late ROman Empire?