The lighthouse of Christianity shines because it is based on the reality of an objective and universal Moral Code that we mysteriously know and have broken, said C.S. Lewis. It is this truth which makes Christianity’s offer of forgiveness, and its gift of supernatural help towards keeping that Moral Code, so incredible.
In this video, Lewis shows that conscience is not an invention of civilization or of great human teachers but is as old as Adam and Eve, and has always been there, witnessing away in the human soul.
http://www.youtube.com/watch?v=bdos6zUk27Q