I would be pleased also with my child reading C. S. Lewis.
He recently read Mere Christianity and he read The Screwtape Letters last year and I think he's quickly becoming a Lewis fan. What a contrast between Lewis and my other son's favorite author, Samuel Clemens. My 17 year old also likes Clemens and I have to admit that I do, too. :-) Over the summer we found Adam and Eve's Diaries and they are a hoot!