A century after the death of Patrick... there were few Romans left in western Europe. [By the mid sixth century] the whole subtle substructure of Roman political organization and Roman communication has vanished. In its place have grown the sturdy little principalities of the Middle Ages, Gothic illiterates ruling over Gothic illiterates, pagan or occasionally Arian—that is, following a debased, simpleminded form of Christianity in which Jesus was given a status similar to that of Mohammed in Islam.
Ch. VI What Was Found - How the Irish Saved Civilization (1995)