I am not a mindreader, and don't claim to know what Hitler truly believed. Frankly, I doubt that he much cared about theological issues at all, what he cared about was megalomaniac ambitions, for himself and Germany.this is a phony narrative, to smear Christianity by association with Hitler. It is a 'reductio ad Nazium' fallacy. But he esteemed islam much more, as a warrior ideology.
But what is undeniable is that his supporters were Christians. Germany was 90+% Christian, predominately Lutheran and Catholic. The folks invading Poland, operating the Holocaust, bombing London, etc. were overwhelmingly Christians.
Of that there is no doubt. And Hitler had supporters across Christendom, well including the USA. Hitler had a framed portrait of Henry Ford in his office.
Tom