In A.D. 313, just one short decade after a massive, bloody persecution of Christians, the Emperor Constantine granted religious toleration to the small Christian churches in the Roman Empire. Flash forward two centuries. In 476, the Emperor was deposed at Ravenna, effectively ending the Roman Empire in the West. On the former date, the empire was vast and Christianity was marginal; by the latter, the empire was fractured, and Christianity had become the dominant religious and social movement in the Mediterranean world.
How?
In his magisterial new study of this era, acclaimed classical historian Peter Brown attributes this transformation to the evolution of wealth and, in particular, philanthropy in Christian churches.