Many people mistakenly think that Adolf Hitler was either anti-religious or an atheist. This is in fact untrue. Hitler saw himself as doing God's work, was inspired by Martin Luther (the father of the protestant reformation), and was in constant contact with the Catholic Church.
Apologists make these claims about Hitler:
- Hitler was an atheist
- Hitler was secretly atheist in private.
- Hitler shows that secularism and atheism are dangerous
- Hitler persecuted Christians
- Hitler was inspired by Darwin
"Hitler was an atheist"
Hitler was, seemingly, not an atheist. Hitler said in his famous book, Mein Kampf, that he was doing the work of God:
- "I am convinced that I am acting as the agent of our Creator. By fighting off the Jews. I am doing the Lord's work."
And in 1938, Hitler declared, "I am now as before a Catholic and will always remain so." Also, the Nazi belt buckle had Gott Mit Uns "God with us" etched on it. To say that Nazi Germany was secular is factually incorrect. (Note:"Gott Mit Uns" was also on German soldier belt buckles under the Kaiser in WW1) Hitler also drew much of his inspiration and anti-Semitic hate from the works of the protestant reformer Martin Luther. For example, in nearly every speech or text that Hitler besmirched the Jewish people, he would make direct reference to "their lies". However, in Hitlers entire career, he never enumerated what the Jewish lies were. This is because the "lies" in question were a part of contemporary Germanic idiomatic language.
That is, when Hitler was speaking to Christian Germans, he could rest assured that they would be very familiar with the "Jewish Lies" as they were made popular by the most renown German author of all time, Martin Luther.
Martin Luther inspired Nazism
In his pinnacle work, On Jews and their Lies, Martin Luther, spelled out very clearly that the lies where the Jewish denial of Jesus as the Messiah. As punishment for the lies, Martin Luther spelled out a program of treatment for the "Jews" that Hitler followed specifically. The seven points that Luther laid out were.
- to avoid Jewish synagogues and schools and warn people against them;
- to refuse to let Jews own houses among Christians;
- for Jewish religious writings to be taken away;
- for rabbis to be forbidden to preach;
- to not offer protection for Jews on highways;
- for usury to be prohibited, and for all silver and gold to be removed, put aside for safekeeping and given back to Jews who truly convert; and
to give young, strong Jews flail, axe, spade, spindle, and let them earn their bread in the sweat of their noses.
These instructions read like the blueprint for the holocaust. This finally included Martin Luther's command that good Christians should kill Jews.
Hitler doesn't mentioned Darwin
- "In fact, Adolf Hitler used Darwin’s theory as philosophical justification for the Holocaust."
There is no evidence that Hitler was influenced by Charles Darwin.  In fact, there's no instances when Hitler even mentions Darwin. The only reference Weikart (who wrote a book specifically trying to connect Nazism to Darwin) could find was a mention by Wagener.
"It's true that Hitler hardly ever mentioned Darwin by name (The only direct mention of Darwin I have been able to find is an account by a colleague Wagener)."
- — Weikart
The Nazi party generally opposed Darwinism.
Hilter made some claims about the struggle for life and racial theory, particularly in terms of prescriptive policies, but these are not part of evolutionary theory, which is strictly descriptive. Also, these notions rely more on earlier thinkers, such as the works of Herbert Spencer.
If nature does not wish that weaker individuals should mate with the stronger, she wishes even less that a superior race should intermingle with an inferior one; because in such cases all her efforts, throughout hundreds of thousands of years, to establish an evolutionary higher stage of being, may thus be rendered futile.
But such a preservation goes hand-in-hand with the inexorable law that it is the strongest and the best who must triumph and that they have the right to endure. He who would live must fight. He who does not wish to fight in this world, where permanent struggle is the law of life, has not the right to exist.
In any case, attempting to falsify evolution based on Hilter's actions are an appeal to consequences, slippery slope and appeal to emotion, which are fallacies. Perhaps more significantly, he mentions Martin Luther many times (both were anti-Semitic) and praises him in 'Mien Kampf'.
Darwinian texts were banned
An exhibit by the University of Arizona library has a list of banned books in Nazi Germany circa 1935, it lists "Writings of a philosophical and social nature whose content deals with the false scientific enlightenment of primitive Darwinism and Monism (Hackel)." 
"Hitler shows that atheism and secularism are dangerous"
Hitler and the Nazi Party was anything but secular. Hitler championed religious indoctrination in public schools, negotiated a treaty with the Vatican in which the Church was able to collect taxes, and made special protection for Catholic churches and priests, which were de facto applied to German protestant churches and ministers.
"Secular schools can never be tolerated because such schools have no religious instruction, and a general moral instruction without a religious foundation is built on air; consequently, all character training and religion must be derived from faith. . . we need believing people."
- — Hitler, April 26, 1933, during negotiations which led to the Nazi-Vatican Concordat of 1933.
"Embued with the desire to secure for the German people the great religious, moral, and cultural values rooted in the two Christian Confessions, we have abolished the political organizations but strengthened the religious institutions."
- — Adolf Hitler, speaking in the Reichstag on Jan. 30, 1934
"Hitler persecuted Christians for their belief"
As the above shows, Hitler and Nazi Germany were neither atheistic nor secular. Christians have claimed that many of their faith were sent to the death camps. The only Christians who were sent to the death camps specifically because of their religious beliefs were the Jehovah's Witnesses, who were pacifistic and a threat to Germany's war effort. Most other Christians in the death camps were the German guards and administrators. Atheists, on the other hand, were targeted specifically for their non-belief and sent to death camps:
"We were convinced that the people needs and requires this faith. We have therefore undertaken the fight against the atheistic movement, and that not merely with a few theoretical declarations: we have stamped it out."
- — Adolf Hitler, in a speech in Berlin on Oct. 24, 1933
The situation was different in Poland. Polish churches were shut down, but this was because they resisted Nazi influence.
There are some cases where Nazism seems to oppose the Polish church which opposed Nazism or restructure other churches. But, these are not anti-religious but inter-religion sectarian fights. Similarly when Henry VIII tore took the wealth of the monasteries and restructured and restricted various church issues he was trying to build a different church, not trying to destroy churches in general.
The Catholic Church Exists Today at the Mercy of Hitler and the Nazi Party
At a time when Hitler's war movement was desperate for cash, so desperate that the gold fillings were individually ripped from the mouths of their victims, Hitler did not touch the Vatican. Not only did the Germans basically occupy Italy for many years, in Sept. of 43, when Mussolini was toppled, the Germans were the only military force in Rome, the land around Rome, and all of northern Italy. Hitler did not order the gold to be stripped from the walls and ceilings of the Vatican. Hitler did not order the worlds largest treasure to be taken from the vaults of the Vatican. Hitler did not move the Pope to Germany, threaten the Pope, nor hold the Pope hostage. The only thing that kept Hitler from rendering the Catholic Church defunct was his own moral imperatives.
"Hitler's Table Talks prove private Atheism"
The main English translation of the Table talks are derived via a dishonest translation by a French conman. 
The general population went along with it
Even if one offers that the Nazis were secret atheists, or just Hitler. They went along with the holocaust and the anti-Jewish rhetoric was highly effective for a population of largely Catholics and Lutherans. Even if it were the case that Hitler was secretly atheist, it was the overt religious nature and antisemitism that allowed him power and which fueled the holocaust.