I see Heidegger's relationship with Catholicism as an arc. He was born to a church sexton and received a Catholic education until university, where he abandoned Catholicism prior to his marriage. Despite reading Luther and St. Augustine, his thinking progressively abandoned any theological aspects. The tendency peaked in the 1930s, when he argued that a belief in God precluded one from authentic philosophy.

Yet, during that period, he also began to anticipate a coming of beyng, a historical event, that he began to decribe in religous terms. In an interview intended for release after his death he famously said that only a god could save man from the path he was on. He was buried in the Catholic churchyard at Messkirch. How far did his thinking follow his body back to Catholicism?

In a recent essay Jean Grodin hints about the end of the arc.

We have recently learned that Heidegger decided that the last writings to appear in the collected edition would be the "black notebooks" (schwarze Hefte) to which he consigned his most personal, and no doubt most revealing, reflections. We may have to wait a few decades for the completion of this edition before we can know the source of the unease that tormented Heidegger as he stirred up the question of Being. One can suspect, with Gadamer, that the unease was in large part religious. The title of the hundreth projected volume of the GA already gives us a little glimpse of its contents: Vigilae. This Latin title also reveals that, for Heidegger at his most secret, the space of thinking was perhaps not exclusively occupied by the Greeks and the Germans.

Striking evidence for this point can be found in a short autobiographical text from 1937-1938 titled "My Path Up to Now," which slipped into GA 66.

And who would want to deny that this entire path up to now was accompanied silently [verschwiegen] by a confrontation with Christianity--a confrontation that was not and is not a "problem" taken up at random, but the preservation of the ownmost origin--of the family house, of the homeland and of my youth--and at the same time a painful detachment from it. Only someone who was so deeply rooted in an actually lived Catholic world can suspect something of the the necessities that affected the path of my questioning up to now like subterranean seismic tremors.

Vigilae means awakening.  ¶ 3:15 PM