There have been far more genocidal acts commited in the name of a religion for a bunch of canned food and money in donations to make up for
Most religions don't condone genocide directly in their texts, but do mandate charity and generosity. It's tyranny using religion as a guise by dictators to seem justified in their goals (along with other subtle force tactics for those who aren't scare). The only leader that comes to mind that probably was actually killing because he thought a deity mandated is Philip II, but there will always be crazy people who occasionally rise to power, religious or not. Eugenics was a product of scientific thought and
scientists to advance natural selection artificially, and it was one of the ambitions of Riddler to commit the holocaust.