The Darwinists are in high dudgeon over the implication in the documentary Expelled that the Nazis were among the intellectual heirs of Charles Darwin.
Nevertheless, if people believe that all morality is subjective; that humans are simply animals with no soul; that there's no imago Dei; that we are locked in a struggle for survival one species against another, one race against another; that some races are more gifted by nature than others, and others more debased; and that killing and extinction are part of nature's grand scheme - then it's easy to see how those people might come to see a genocidal holocaust as consistent with the way the world is and not at all "wrong" in any moral sense.
Darwin believed all of these things and though he himself would have doubtless recoiled from any genocidal implications, some of those who were influenced by him were prepared to follow the logic all the way to its grisly end. Darwin's ideas, as distinct from his own character, were completely compatible with the thinking of the Nazis. Given the truth of Darwinian materialism might makes right and there is simply no inconsistency in promoting the "final solution."
On the other hand, it's hard to see how the holocaust could ever come about in a world in which people believe that there is an objective, transcendent right and wrong; that man is created in the image of God and that all men are equally loved by God; who believe that there is no innate competition between races or species but all were created to live in harmony with each other; that death is an evil intrusion into the created order rather than part of the normal order of things and that deliberately killing innocent women and children is morally abhorrent.
Had the Nazis and the German people fervently held those convictions the holocaust would never have happened, and had that set of convictions prevailed anywhere else that there have been similar genocides before and since the German atrocities, none of them would have ever occured either.
Genocide, at least in the West, has almost always been carried out by people who hold to the same worldview as Charles Darwin did. Maybe there's something wrong with the worldview.RLC