Since I don't have a subscription to 'First Things', I lifted this straight from Keith Burgess-Jackson:
Dietrich von Hildebrand
"I just mentioned Nietzsche. There is one important point on which Hildebrand is in accord with Nietzsche. The Enlightenment had thought that one could eliminate the Christian God, and indeed eliminate God altogether, and still have morality, the same morality that Christians had upheld. Nietzsche was one of the first to see through this incoherence of thought. He pointed out that even so elementary a moral norm as respect for truth can no longer hold its ground once God is dead. What Nietzsche said about morality, Hildebrand says about man: Cut off from God and debunked by the reductionist philosophies of the eighteenth and nineteenth centuries, man no longer occupies any special place in the world. For a time, man might retain a sense of some special dignity, but this is the last light cast by a setting sun. If God is dead, then the Hitlers and Stalins of the world are just treating human beings according to what they really are. It follows for Hildebrand that if we are going to take a principled stand against the totalitarians, we should not waste our time trying to restore Enlightenment civility, which is an ideal lacking in inner coherence; we have to go further back and do a much more radical work of retrieval and renewal in our thinking about man. “All of Western Christian civilization,” Hildebrand wrote in his review, “stands and falls with the words of Genesis, ‘God made man in His image.’”"
(John F. Crosby, “The Witness of Dietrich von Hildebrand,” First Things [December 2006]: 7-9, at 9)
I think it was C.S. Lewis that stated something along the lines of Western culture 'still living in the shadow of the faith, although no longer having the faith.'
There are other competing 'penumbrae' as well, working to eradicate all vestiges of the Christian shadow while denying any responsibility for the resultant barbarity.