Start of Vasilief : History of the Byzantine Empire 

The empire from Constantine the Great to Justinian

The conversion of Constantine 

Historians and theologians have been primarily interested in the causes of Constantine’s “conversion.” Why did Constantine favor Christianity? Should his attitude be viewed only as an indication of his political wisdom? Did he see in Christianity merely a means of gaining his political aims? Or did he adopt Christianity because of his own inner conviction? Or, finally, was this “conversion” influenced by both political motives and a spiritual leaning toward Christianity?  

Vasilief : The Conversion of Constantine: read complete. More Byzantine resources / Constantinople ||| Greek Library