Christopher Dawson’s history Religion and the Rise of Western Culture continues to be one of my favorite primers on the medieval world. Despite its datedness (first published in 1950), its synthesis and overarching argument for the role of religion in the development of post-Roman Europe has not lost any of its poignancy or relevance.
Also, Dawson’s analysis proves to be prophetic for our contemporary Western world. In the introduction to his book, he writes:
It would be a strange fatality if the great revolution by which Western man has subdued nature to his purposes should end in the loss of his spiritual freedom, but this might well happen if an increasing technical control of the state over the life and thought of its members should coincide with a qualitative decline in the standards of our culture. An ideology in the modern sense of the word is very different from a faith, although it is intended to fulfill the same sociological functions.