Ahhhh.........
The old debate that inevitably pops up when people start to realize that not all is what it seems in the time honored perspective of good and evil.
Truth: Don't know any.
But anyway, if you look back in history you see countless cases of this very phenomenon.
WWII: The rest of the world disagrees with what the Nazi's did right? Well, they thought they were doing the right thing. They honestly believed in what they were doing. Also... Anyone here like Martin Luther (Not King... the one known as the Reformer in the 1600's). Well, Luther wrote a treatise on the Jews that was later used as a model for Hitler's actions. Read it if you get the chance, it's mindblowing (Martin Luther's On the Jews and their Lies)
Too often in history the side that is "good" wins because they're the ones that get to write the History books. If Hitler had won WWII we would all have learned about the Nazi party's great and God lead crusade against the world.
Another thing to do is Watch Kingdom of Heaven. It's the same sort of Story, both sides tout the phrase "GOD WILLS IT!" to rally themselves.
Something Real: Humans are incapable of truly knowing right from wrong. I believe that the eventual harm that is committed is a good indicator of evil actions, but they must be balanced against the concerns of the individuals. But that's just me. I may be totally off my rocker, I'm human and I accept that.
I also believe in God and Jesus Christ, but I recognize the right of others not to, and I entertain the idea that I may be wrong. I think God wil judge me as She will.
Truth: Decide for yourself.