Awhile back I outlined C.S Lewis' main points in books one and two of Mere Christianity for my own uses. It is one of my favorite books and so although I probably won't do it justice, I'll reproduce it here for anyone who hasn't read the book and is interested in the kind of direction it takes.
- Humans have a common standard of behavior and realize they cannot live up to it. Lewis calls this The Law of Nature or the Moral Law
- The moral law is not an instinct, it is what chooses between instincts. The moral law is not social convention because morality can be compared to a standard. If it were social convention, then the idea of moral reformers would not exist
- The moral law is not an evolved adaptation to living in groups (i.e. decent behavior benefits society). Why should individuals care about society?
- In the one case where we can try and see if there is anything more than matter to the universe we find that there is. This is our notion of the moral law.
- If there were a power outside the universe we would not expect it to be one of the things inside the universe but rather an influence (the moral law), which is what we find.
- If indeed there is a power behind the universe and this power instituted the moral law, then it must be dissatisfied with us since we fail to live up to that law. That is the fix we are in
- Atheism is too simple since it posits that the universe has no meaning. To discover it has no meaning, one would have to have an idea of justice, which wouldn't exist without the moral law
- Only Christianity and Dualism deal with the reality that men find much of the world to be bad and some meaningless. Christianity claims a good world spoiled while dualism claims equal and opposite powers on a battlefield. Dualism doesn't work, however, since you need to introduce a third thing to judge between the two powers. Christianity rings true since in our experience badness is always goodness pursued by the wrong means or twisted
- The conclusion that evil is derived immediately raises the issue of God's all powerfulness. If He is so, then why is there evil? Here enters Free Will. God apparently thought it worth giving creatures like us the freedom to reject him. But God left men with several witnesses; a) conscience, b) myths of dying Gods ("good dreams"), c) a chosen people to bring his message and ultimately the answer to man's rebellion. And Jesus claimed to be God and to forgive sins. Ultimately you must decide between Lord-Liar-Lunatic (the trilemna)
- So what did Jesus come to do. He came to reconcile our since to God. How he did this is not important, only that he did. He became the perfect penitent because we in our sins could not repent fully
- So how does a man appropriate the atonement? By belief and the sacraments (in CSL's view). So then how are those who haven't heard of Christ saved? We don't know the complete answer. Why did God come in such a disguised fashion? To preserve free will
There's obviously alot more there but I was trying to distill the main points.