In technical terms, the study of defending your faith in Christ is called apologetics. I know that some Christians are more inclined to think and read in that realm more than others. If you are one of those people, I think you will be very interested in The Reason for God. It is written by Tim Keller, a pastor in New York City. I am several chapters into it, and have already been greatly encouraged and enlightened. It is somewhat in the genre of C.S. Lewis, but much easier to read.
One more thing, Keller has a website concerning the book that you might want to check out.
So, happy reading!
P.S. I was at Borders tonight and took this picture!