Apparently I do not read enough banned books!
I think A Clockwork Orange, tops my list, which I consider one of the great works of Christian-themed literature from the 20th Century.
Harry Potter holding the Number 1 spot (which Rowling has stated she is proud of), is another great Christian-themed work, with The Deathly Hallows being the second-best fantasy novel I've ever read. I actually started the series because my church showed a video condemning various pop-culture works as "evil" or "against God." Not only was Harry Potter included, but it was the whole reason the video had been made in the first place! (I highly doubt the authors of the video had even seen the TV shows and movies or read any of the books they so righteously condemned.) Because I believe the Christ of "come and see" wants us to make decisions for ourselves, I decided to do just that with Rowling's series, and am I ever glad I did!