"All a man's ways seem right to him, but the LORD weighs the heart."
Does any man truly believe that what he does is evil? Surely if a man thought his actions were wicked he would not do them. Or perhaps he knows what he ought not to do, but finds some reason to justify his doing it and therein he does what he believes to be right? Truly no one does what is evil in their own eyes but only what they can justify.
It is no wonder then that we are not fit to judge each other, for each person only does "what is right for them" and what is "right for them" isn't always "right for you". Hitler told the German people that he wanted to create a supreme race. Not a bad idea on paper, but we didn't see death camps.
Maybe we would tell him today that he has a right to his beliefs and although we might disagree, we each must only do what we think is right, but that's how wars start: two groups working towards opposite ends each doing what they think is right.
A world of relative morality is chaos.
Only one sovereign over humanity can set order for us. God is the only one capable of judging us because he can see our hearts. We know God to be righteous fair in his dealings because of the Cross. We trust that he is just in order to be the one who justifies us.