Both his fiction and non-fiction are well worth reading. The 7 Narnia novels offer a beautiful view of Christianity that make for very easy reading. The 3 Prelandria novels ('Out of the Silent Planet, Prelandria and That Hideous Strength) offer a more adult perspective - and the final scene in Prelandria is a celebration of sexuality in a way that is largely unique in any literature.

The Screwtape Letters - the writings of a senior demon to a junior in active service on Earth are an outstanding insight into the confusions that we can get ourselves into.

His non-fiction material is largely designed to provide an intellectual basis for Christianity, and still reads well. 'Mere Christianity' is perhaps best known.

I hope you do read at least some of them - definitely quality theology in a very accessible form.