I don't think of people as "evil," unless you think of evil as just on the spectrum of "bad," rather than the "inhuman/devilish" thing many paint it as, for the reasons said above.

Is it a weakness? I guess if you look at it as spiritual malaise, and one gives in to it, then probably yes. Though I think as someone with a long history of depression, that "weak" is a bad word as we do not always have a choice when sickness comes upon us. But "sick" is a good word, for the paradigm you hold.

And that begets the question, "If you knew it is evil, would you still do it?" And only psycopaths would answer yes. So now we get to the question of the source of knowledge and truth here. That whether it is a matter of disagreement, or of lack of knowledge.
The spiritual path, especially the deist side of it, is very clear on it.

I do not belong to that path. And yet I still hold you can tell what is "morally wrong." Always something to think of.

As for the "laws of beauty," that way lies many an atrocity, in those who think despicable things beautiful, or that an end-goal of beauty is worth despicable acts to reach it. Hm.