"evil" is an abstract concept defined by the "norm" of societal behavior in the group doing the defining. thus, it is relative. slavery is "evil", unless you're an antibellum plantation holder, or an ancient roman or greek, or a modern day wealthy haitian, as but a few examples. murder is "evil", unless you're a bomber pilot dropping incendiaries on a civilian population of your "enemy". eating meat is "evil" if you're a member of PETA.