I already explained a little how atheists can't call anything evil

All religion is DEMONSTRABLY the invention of humanity; therefore, all the moral codes and Good & Evil are Atheist by default. Such an instinctive morality underwrites our familial / societal / tribal codes and relationships in terms of altruism and empathy; they are innate as language and music, and might be found in the Humanist Teachings of Jesus as the simple universal absolute of Do unto others as you would have them do unto you. This is something we struggle with for sure - after all the Good / Evil duality is encoded as deep as the Nature / Nurture debate - but it is something we also FEEL pretty deeply too.