The process was one of a progressive eclipse of Christendom by Europe (defined as a geographical notion in a relationship of distance with other parts of the world). The two entities differed fundamentally. Christendom claimed the loyalties of those who were baptized into the belief-community and who related to the outside world accordingly. Europe, on the other hand, claimed no unity beyond the geographical landmass that it represented and an emerging sense of the moral and civilizing superiority of the different states and peoples which occupied it. Western Christendom was a great project about European unity, over a millennium in the making. Its destruction, by contrast, was rapid and total. In little over a century, there was nothing left but the dream of it.

— Mark Greengrass. When Hilaire Belloc (famously) said "Europe is the Faith, and the Faith is Europe," he had it precisely wrong.