Boomer "Evil" suggests the opposite of "good". Deity isn't necessary to understand that concept you're correct, but what defines or separates one from the other?
Hitler didn't think what he was doing to the Jews was "Evil" he thought it was something necessary to establish Arian supremacy.
What made his personal ambitions "Evil". seems to me we first need to define exactly what "Evil" what it is boomer before you can just dismiss it as some abstract idea my friend.
What do you tell your kids is "Evil"?
What makes it so?
Explain.
Ask those last two questions of yourself. Lots of people will say "X, Y and Z are evil and I believe that because God says so in the Bible." And if a non-believer says "X, Y and Z are bad because I think they're bad" other people will say "You have no standard for what is bad, you say it's bad just because you say it's bad."
But the thing is, the person that says X, Y and Z is bad because the Bible says it's bad are doing the same thing. Their standard is the Bible but it is THEY that are determining the standard. They could just as easily have picked a different standard that said X, Y and Z are not evil.