Hitler? AFAIK, he was a theist all his life.
He was educated at a Benedictine school, sang in a catholic choir, and had thought for a while, when young, to become a catholic priest. It has been frequently argued that he was, at the end, a theist, but the evidence is thin. He did want to replace both the catholic and protestant churches in Germany with a volk-church, but the suggestion that this was to have been a non-christian volk-church is, at best, unsupported and unlikely.