The question tackled by the "Face-Off" participants was a provocative one: Does Satan exist? If so, is he a fallen angel or is he some sort of formless malevolent force in the universe? And if he doesn't exist, how do we explain why there is so much pain, suffering and violence in the world today? The discussion brought up a whole series of fascinating and fundamental questions about good and evil, about human nature and the nature of God.
(Karson Yiu/ABC News)