There is no such thing as pure good or pure evil, least of all in people. In the best of us there are thoughts or deeds that are wicked, and in the worst of us, at least some virtue. An adversary is not one who does loathsome acts for their own sake. He always has a reason that to him is justification. My cat eats mice. Does that make him bad? I don't think so, and the cat doesn't think so, but I would bet the mice have a different opinion.