Right and wrong
Some things are really wrong.
Betraying a friend who trusted you. Picking on someone who can't fight back. Those aren't just unpopular. They're wrong everywhere and for everyone, even if everyone around you called them fine. So where does a “wrong” like that come from? People usually give one of four answers.
Instinct might explain why we feel that cruelty is wrong. It can't make the feeling true. If morality is only instinct, “cruelty is wrong” is a strong feeling, not a fact.
Then no culture could ever be better than another, and the people who ended slavery weren't right, only different. Almost nobody believes that.
Then “wrong” only means “I don't like it.” But when someone cheats you, you don't say you dislike it. You say it isn't fair, as if there's a standard they should have kept.
Then “wrong” means what it says, for everyone, whether they agree or not. And a real moral law points to a real lawgiver. Paul said it long before: God's law is “written on their hearts.”
Romans 2:15This is the question that turned C. S. Lewis, an Oxford scholar and a convinced atheist, toward God:
My argument against God was that the universe seemed so cruel and unjust. But how had I got this idea of just and unjust? A man does not call a line crooked unless he has some idea of a straight line.