Although Adolf Hitler is our guiding star, in his book for the masses of Protestant and Catholic Germans, Mein Kampf, he wasn’t entirely outspoken insofar as it is not an anti-Christian manifesto. More entertaining is Hitler’s Table Talk (our translation of the introduction to the German edition can be read here).
I would also suggest the book of Hitler’s priestess Savitri Devi, who, after the catastrophe of 1945, came to grasp the spirit of Hitlerism perfectly. See my abridged Memoirs and Reflections of an Aryan Woman (the full text in French can be read here; the complete translation into Spanish, here).
See also my excerpts of Brendan Simms’s Hitler and, regarding Hitler’s pantheism, see these excerpts from Hitler’s Religion by Richard Weikart.