It has become increasingly clear to me lately that far too many Americans are under the impression that Nazis were largely motivated by religion to exterminate the "Christ-killing" Jews. I urge anyone listening to learn the truth (http://en.wikipedia.org/wiki/Religion_in_Nazi_Germany is a good place to start) and educate their friends.
The reason I believe this is important is that people make important, life-changing decisions based on their understanding of the past. The Holocaust is generally used as an example of humanity's worst. It's not that the Holocaust is somehow unequaled in terms of atrocity, but in our Western European-centered culture we rarely look far enough back in history, or far enough around the curve of the world, to get the "big picture." So we focus on the Holocaust. If we are under the erroneous assumption that religion caused the Holocaust, we are more likely to become irreligious, or even anti-religious, both personally and as a nation. In my opinion, this would be counterproductive and dangerous. And if you think that a democratic nation for whom religion has played such an enormous role couldn't possibly become anti-religious, the rise of Nazism (anti-religious) in Germany (formerly a democracy, and seat of the Reformation) should be sufficient to show otherwise.
However, if we follow the research that's been done on such atrocities, we can focus on things that really will help us to prevent another Holocaust: limiting governmental power, promoting democracy, and resisting war.