Matthew Rose, in an article (click here) in the March 2018 issue of First Things, discusses what he calls "the Anti-Christian Alt-Right." He identifies three key thinkers: Oswald Spengler, Julius Evola, and Alain de Benoist. The connection between Spengler and Evola is perhaps less certain than he suggests, but he is right that all three thinkers are key, and Evola and de Benoist, at least, were anti-Christian. And he is also right that they matter: "The alt-right is not stupid. It is deep. Its ideas are not ridiculous. They are serious."
A book on The Key Thinkers of the Radical Right, forthcoming from Oxford University Press and edited by Mark Sedgwick, covers Spengler, Evola, de Benoist, and thirteen more thinkers whose ideas are indeed serious, whether one likes them or not.