And while I think that Median's vague proposal regarding morality fails and will continue to fail miserably no matter how much he attempts to bolster it, I think that most atheists and theists condemn the Nazi's due to similar considerations (e.g. the inherently warranted value of human dignity). The only difference between an atheist and a theist is that the theist claims that while basing morality on human dignity is a coherent means of construing moral epistemology, it seems ultimately meaningless if not grounded in the existence of a supreme being. So I think that atheists and theists for the most part will come to similar conclusions regarding what is right and wrong, but they will differ on what they feel is necessary to ground those conclusions.
It isn't meaningless to me. Ultimately or otherwise. My willingness, or in fact, my desire, to be humane and kind and compassionate and to not put myself above others out of ego or a false sense of superiority, has a lot of meaning. To me. And since I'm not one that, therefore, picks up a gun or a knife to weed out those I could have chosen to belittle or dehumanize or hate because I have no principles, I think there is a lot of meaning to my godless reasons. Human reasons. Which, as far as I know, are the only ones available.
Being that religious morality gets handily set aside nearly every time there is a war and an enemy to destroy, I think it is high time that we humans own our moral standards, rather than blame them on something else. I happen to like moral standards that leave the most people alive and free. Others like ones that cause death and destruction. That is our human problem, and we deal with it daily. Pretending there is an outside force involved, that both judges and justifies, kind of messes up the whole thing and excuses many a horror. Such as the aforementioned Nazi atrocities.
Religion isn't the only human failing to cause such events. Worship and fear of anything/anyone including individuals like Genghis Khan and Stalin and Mao and the various N. Korean Kim's is proof that we humans are pretty adaptable when it comes to being or following assholes. But religion often helps, with its external first cause too often busying itself as it makes up shit and hands out the bullets.