Well I have a few views on this.
1. Superman was raised by Christian parents so... he's Christian.
2. Isn't Superman kinda immortal?
3. I hope he burns and rots in a Hell filled with krypnonite!(yes, my last name is Luthor)
4. He fought against Hades and other "gods" I think.
5. Pascal said(moving away from Sman) that it's better to live your life as if God exists, because if you don't, then find out you were wrong, and He does exist the consequences are...well ya know...
6. Join The Cult of Alderbranch if you want salvation, oh ye of little faith, I the Mad Prophet/ High Oracle of The Cult of Alderbranch have seen the future and glory(and life and liberty) belongs to those that follow us!