Because of his importance to history, and his oft-described sense of messianism at the time of his early successes, I think some people often look to Hitler to provide evidence of a comprehensive philosophy, which would include things like his religious views.
But I am not sure that knowing what he thought about any religious or philosophical subject is of any more value than knowing what anyone of a substantially maladjusted psyche thinks on the matter. Hitler was both a megalomaniac and a fantasist. I am certainly not prepared to attach any value whatever to knowing the religious views of such a troubled individual. For all practical purposes Hitler was the personification of evil. Attempting to divine from his writing or speeches some kind of devout motive, behind his warped ideas, seems to me entirely ridiculous.
We do know that he had been brought up, at least nominally, as an Austrian Catholic. But Hitler's expressed religious beliefs in Mein Kampf and elsewhere do not follow any consistent pattern. He would bore the staff at his HQ with lengthy dinner monologues about the history of mankind, the nature of the cosmos, interwoven with narcissistic stories about his youth in Vienna, and his "struugles".(Kershaw). He would repeat endlessly his justifications for anti-Semitism, which as Alan Bullock points out borrowed heavily from attitudes of some red-necked Austrians of the early-twentieth century, and especially the visceral prejudices of the gut-right-wing elements of some of the German-speaking petit bourgeoisie in cosmopolitan Vienna. This corresponds with the time Hitler was a down-at-heel artist, mixing with ne'er-do-wells in down-market cafés and doss houses. Almost certainly he did not have the capacity and mindset to develop and sustain a consistent religious position, radically outside of the mainstream. As far as I know, he was not a man given to spiritual reflection.
During the days of his youth, when he was trying to make it as an artist, Hitler pretended to intellectual thought - but based on Bullock's assessment it was shallow. The milieu in which he lived during this period of his life i.e. the time when many young people give thought to life's big questions, was hardly conducive to the sort of profound thought and discussion necessary for developing religious and philosophical positions.
It is also worth remembering that Hitler, though he did not lack for political cunning, was not an academically educated man. (Before he became a politician he had been a corporal in the army.) There is ample evidence that he was ill-at-ease in educated company. He was far more comfortable in a beer hall - especially if he was able to grab the floor, and, heaven-forbid, a microphone.
Hitler's religious utterances throughout his life tend to be disorganised and haphazard, perhaps not unlike the expressions of someone not tied into a church structure, and lacking the disciplines of higher education. Nor do they indicate any particular personal religious commitment.
There were times when the Nazi regime was embarrassed by the criticism of religious people, such as when sections of the public became aware of the extent of the euthanasia programme. Kershaw* ,reporting on Hitler's attitude around the end of 1941, says "there would be no place in this utopia [an "eastern Reich covering most of Russia] for the Christian churches". And Goebbels in his diaries commented at the time 'There is...an insoluble opposition between the Christian and a Germanic-heroic world-view'. Later Kershaw (p516) records Hitler as having indicated his determination, (Spring 1942) "after their insidious behaviour during the winter...to destroy the Christian Churches after the war". And when he was persuaded that the Vatican was deeply inplicated in the plot to oust Mussolini, in a military briefing, Kershaw says that he talked wildly of occupying the Vatican and "getting out the whole lot of swine". (Kershaw p596)
The religious question had bedevilled German unification for centuries, and one of Hitler's predecessors, Otto von Bismarck, (Chancellor 1871-1890) had pursued a Kulturkampf against Catholics, in which the term Reichsfeind (Enemy of the state) had been widely employed. The notion of a cultural "enemy within" was not therefore new to recent German history. Thus it was that politicians who wanted to succeed as badly as Hitler, needed to tread carefully as between Protestants and Catholics in a Federal Germany.
It would appear from reading historians such as Kershaw* that there was religious pressure - notably from Catholics - on the regime from time to time, but the Nazi authorities were careful, it would seem to keep it under control and it was not allowed to develop into a contest.
Events may to some extent have followed a pattern set in the later 19th century, where religion in Germany, as elsewhere in Europe, had undoubtedly been challenged by intellectuals. The writings of German philosophers such as Marx, Hegel, Nietzsche, as well as scholars elsewhere, such as Charles Darwin, feed into the general zeitgeist of the defeated post-war nation, and undoubtedly influenced the climate in which National Socialism prospered. Hitler's pot pourri of ideas and expressions borrow variously from these different sources.
Who knows what Hitler would have become had he ultimately been successful, and what path he might have taken as regards the churches? He would not have been the first German Chancellor to have taken on the Roman Catholic Church if that had been his plan. So in answer to the question, I believe that while Hitler, like many in society, would have had a perfunctory religion of Catholicism, any beliefs associated with his divers utterances on the subject, from time to time, were held more in service of his political ambitions than for personal reasons. Hitler's only really compelling ideologies were national socialism and German world domination
*Ian Kershaw; Hitler 1936-1945; Nemesis (London 2001).
*Alan Bullock; Hitler: a Study in Tyranny (London 1962).