Here are eleven books that I think would inform any study of Christianity. I was inspired by this post:

1. Mere Christianity- C.S. Lewis. This book is fundamental for anyone who thinks about Christianity at all. It is written to the unbeliever and the believer, and it begins its approach to the subject of belief from a non-religious starting point. Essential.
2. Knowing God- J.I. Packer. This will get you thinking deeply about the faith you have signed on to.
3. Reasonable Faith- William Lane Craig. The very best book I have found on thinking through doctrine and apologetics for the layman (which I am). Be prepared for some very thinky stuff here.
4. Why I am a Christian- John Stott. Thinking through the reasonableness and the real experience of being a follower of Christ.
5. The Case for Christ- Lee Strobel. Excellent and accessible apologetic. I have recommended it and given it away many times.
6. The Case for Faith- Lee Strobel. Mr. Strobel’s basic apologetic for faith tackles the thorny questions.
7. Why I Am a Christian: Leading Thinkers Explain Why They Believe- Edited by Geisler and Hoffman. I want to share the table of contents here for the scope of this book, but WordPress is not allowing it at the moment.. Chapter 3 by philosopher and former atheist J. Budziszewski : Why I Am Not an Atheist is worth the price of the book many times over; it demolishes atheism from the inside.
8. The God Who is There- Francis Schaeffer. This book is rough going but ought to be required reading. If you want to stop scratching your head over the sorry state of the world and why people think the way they do, read this book. The Line of Despair, say no more.
9. True Spirituality- Schaeffer. Even rougher. This book will make you dig deep into your own foundations, take them apart and start over. Beware.
10. Genesis in Space and Time- Schaeffer. Jesus Christ was a real person in a specific time in a real geographical place; the implications are just as real.
11. The Reason for God- Timothy Keller. We found this so helpful on difficult subjects, and so insightful, that my husband and I used it for a book study with a group of young people at our church.