One further example:
Let’s say that you lived in an isolated island where you had never heard of religion. Indeed some socities do exist like this. In most cases you would find that many are already following natural law. They see cheating, stealing, killing, and so on as wrong. Who told them it was wrong? Natural Law is already written in the hearts of men. To this day I don’t think we have found a society that is doing confirmation or something like that.
Hope this helped.