>> There is nothing in the theory of universal gravitation to oppose Nazism either. I don't believe in a god. Why should that bear on any political movement? <<
I'm sorry; I need to re-assert my context more as I drift from one respondent to the next. Please believe me that I am not trying to assert either that (1) atheism inherently leads to atrocities like Hitler, (2) any individual's atheistic belief system bears similarities or vulnerabilities to Nazism, or (3) any given atheist belief system inherently is responsible for Nazism.
The context was whether Hitler was Christian or Nihilist, and whether such Nihilism as Hitler's can be considered a subset of Atheism. Since Christianity is defined by rejecting certain actions inherent to the Nazi system, one doesn't need to get bogged down in debates over Hitler's contraditory and dishonest statements. Hence, we can eliminate the possibility that Hitler was a Christian. There is nothing in atheism which similarly inherently precludes the possibility that Hitler was an atheist, so Hitler may, on the basis of his actions, be an atheist.
That alone does not prove such a case. I also admitted the possibility that Hitler's nihilism may reject atheism as having certain beliefs, even those beliefs are in the absence of something (a god), or that Hitler may subscribe to some sort of Roman self-deificiation.
Martin Luther preached the enslavement of the Jews and the mass execution of Rabbis. Following the logic above, one concludes Martin Luther was not a Christian. That makes the fact that major Christian denominations are to this day named after Martin Luther a bit problematic, no?