Heidegger's own mystical tendencies are all too often enlisted toward theological ends, although he made clear on many occasions his own views of such misappropriations, especially when considering philosophy's prior churchly service as handmaiden.Go check it out. The post includes a short clip from the The Ister.
Even so, he had the (as is related below by the Dominican friar Reiner Schuermann, later a professor at The New School for Social Research after leaving his religious order) perhaps unfortunate habit of talking of "ineffable experiences" and the "Something Else of which philosophy itself can no longer speak." In other words, that it might be possible to stop doing philosophy, and still have something to say about it after the fact.