Auschwitz anniversary thoughts: a caveat

A caveat: in my writing and preaching and teaching, I almost never reference the Holocaust. And I'm beginning to question my motives. I'm wondering if the reason I avoid the topic is because I think that the people I'm talking to are incapable of contemplating / accepting the reality of human evil in that scope. Maybe I'm incapable too: it doesn't fit with the optimism that I try to live my life with.