1. The Return of the Prodigal Son by Henri Nouwen. My youth pastor preached a series on a weekend retreat based on this book, and I later read the book itself. The messages were some of the most powerful I had ever heard, about God's love, about art and faith, and about myself as the older brother.
2. The God Who Is There by Francis Schaeffer - this book was the first I encountered that addressed the kind of existential questions about faith that I began having in high school.
3. The Cloister Walk by Kathleen Norris - Norris joins Madeleine L'Engle on the list of writers I would christen saints. I love each of her books, but this was the first I found, and is probably the one that speaks most deeply to me about prayer, place, and the life of faith.
4. The Challenge of the Disciplined Life: Christian Reflections on Money, Sex, and Power by Richard Foster. Money has divine properties. We can serve money as god by giving it too much power, whether by extreme thrift or by extreme greed. This book provided a deeper way for me to understand money, sex and power than the church was giving me at the time - especially on sex, where teenagers are pretty much just told, "don't do it."
5. The Hungering Dark by Frederick Buechner. Buecher helped me know what to do with my doubts. He said that every day I had to ask myself if I could believe in Jesus, and that some days the answer would be no, and that was ok.
6. Rich Christians in an Age of Hunger by Ron Sider. I have a very uncomfortable relationship with American (and my own) prosperity. This helped me begin to understand what to do about it.
7. The Divine Conspiracy by Dallas Willard took me months to read, because I could only read about three pages at a time, and then I'd have to stop and think about it. So profound.
8. Surprised by Hope by N.T. Wright. Heaven makes so much more sense after reading this. I wrote more about it here.
9. Jesus Through Middle Eastern Eyes by Ken Bailey. When you grow up with the Bible, it gets hard to read the stories with fresh eyes. This book allowed me to do that, and to understand things I had never gotten before. More about him here and here.
10. Daily prayer books. For the last decade, I've done best praying with a guide. The Book of Common Prayer, John Baillie’s A Diary of Private Prayer, Valley of Vision, and CommonPrayer: a Liturgy for Ordinary Radicals are the ones I've used most.
Have you read any of these? What books have formed your faith the most?