In this article, Lenny Flank, aka. "Darwin's Pit-Bull", takes a look at the claim and actually looks up what Hitler wrote in Mein Kampf.
The creationists are apparently unaware of the fact that Stalinist Russia rejected Darwinian evolution as "bourgeois" and instead embraced the non-Darwinian "proletarian biology" of Lysenko and Michurin (a disaster from which Russian genetics and biological sciences has still not completely recovered). As for Hitler, even a cursory reading of his book Mein Kampf reveals that the true source of Hitler's inspiration and exhortations came from a source that creationists, understandably, would rather not talk about.
Hitler's goal was the "purification" of the "Aryan race" through the elimination of "subhumans", which included Jews, gypsies, Asians, black Africans, and everyone else who was not a white Aryan.
Rather than basing his racism on any evolutionary theory, Hitler based it squarely on his view of white Aryans as the favored people of God. In fact, Hitler solemnly declares that his program of removing Jews and other "subhumans" from the earth is a divine task forced upon him by the Lord Almighty: "What we must fight for is to safeguard the existence and reproductionof our race and our people, the sustenance of our children and the purityof our blood, the freedom and independence of the fatherland, so that our people may mature for the fulfillment of the mission allotted it by the Creator of the universe."
Hitler concludes: "Hence today I believe that I am acting in accordance with the will of the Almighty Creator: by defending myself against the Jew, I am fighting for the work of the Lord,"...
Well, OK. Maybe Hitler didn't mention evolution. What about other hate groups?
The invocation of God and the Bible in support of racism continues with modern hate groups in the US. Aryan Nations, which also calls itself the Church of Jesus Christ Christian, begins its web site by proclaiming "Praise Yahweh" and its intention to "serve the Lord of Glory and His Holy Race". The American Knights of the Ku Klux Klan note that only those of "Christian faith" can be members, and asks every new recruit "Do you believe in Jesus Christ?" The White Camelia Knights of the Ku Klux Klan declare that "at some point God's people must take action in the defense of our Christian, racial and political beliefs".
None of these racist websites mentions "Darwin" or "evolution" as a justification for any of their beliefs. All of them talk about "God" and "The Creator" instead.