The effect on Constantine the Great made on your society today?

Emperor Constantine the Great, known for his hallucination-induced battlefield conversion to Christianity, made religious persecution illegal throughout the Roman Empire. This allowed Christianity to flourish and eventually become the dominant religion of Western Europe.

Because of Constantine, the Catholic Church established itself throughout the Roman world, and stayed there after the Empire fell.

Medieval society was completely dominated by the church: cathedrals popped up everywhere, monasteries maintained and recorded history and scientific knowledge, and the Pope had as much influence of most kings.

In short, Constantine influenced medieval society by handing the future over to the Christians.