Hitler was a member of the Thule Society, a German occultist group, which he used to set the basis of the NSDAP, he also claimed to be a Christian "As a Christian I have no duty to allow myself to be cheated, but I have the duty to be a fighter for truth and justice." I think he used religion to gain more popularity from the German people.
Personally, it's not God I dislike, it's his fan club I can't stand.