國教
Much of the basis of the post-Roman cultural world had been set before the fall of the Empire, mainly through the integration and reshaping of Roman ideas through Christian thought. The Greek and Roman paganism had been completely replaced by Christianity around the 4th and 5th centuries, since it became the official State religion following the baptism of the emperor Constantine I. Roman Catholic Christianity, served as a unifying force in Christian parts of Europe, and in some respects replaced or competed with the secular authorities. The Jewish Christian tradition out of which it had emerged was all but extinguished, and antisemitism became increasingly entrenched or even integral to Christendom. Much of art and literature, law, education, and politics were preserved in the teachings of the Church. The Church founded many cathedrals, universities, monasteries and seminaries, some of which continue to exist today.