1) The Prophetic Imagination by Walter Brueggemann
This book changed the way I read the Bible. Brueggemann is responsible for the social reading of the Bible that I have developed over the past couple years. There isn't a page where something profound isn't said. It's hard to come up with something to say that encapsulates this work. It's just so good.
2) The Suffering of God by Terence Fretheim
I read this during a biblical prophets class and it changed the way I think about God. It put into words what I had been feeling for so long: God shares in my suffering. It was also the first book that subjected me to open theism. Fretheim is a master and has been one of the most influential theologians in my life.
3) The Great Divorce by C.S. Lewis
The imagery in this book is just amazing. Lewis articulates ideas so well through the images he uses. The artistry is masterful and the book is profound. I read a chapter of it when I was in the emergency room after a suicide attempt and found it not only moving but incredibly encouraging. This is a book I will read again and again throughout my life, and I expect to always gain insight after insight through each reading.
4) Love Wins by Rob Bell
This was perhaps the first book that radically altered my theology. At the very least, it affirmed the kinds of questions I had been asking for years and encouraged me to dig more. It is also the book that is responsible for me eventually embracing the theology of universal reconciliation. Even if you don't agree with everything he says (which I don't), it is a challenging book that has a lot to teach.
I should also mention Velvet Elvis here, which should probably also be on this list, as it was the first book that subjected me to the importance of studying the historical context of the Bible. I realized through reading the book how much I love doing that and that I wanted to do it in the future. Bell, through these two books, made me passionate about digging deeper into biblical study.
5) In the Name of Jesus by Henri Nouwen
While it wasn't the first Nouwen book I read--and such a first probably deserves to be on this list because Nouwen is that amazing--it's the one I return to the most. It's so simple, so short, and yet it's another book that doesn't go a page without saying something profound. You could read it in one sitting, but I would recommend taking days to read it, ponder it, and let it sink in.
6) The Prophets by A.J. Heschel
Like The Prophetic Imagination and The Suffering of God, this is a book I was exposed to during my prophets class. And like them, it radically changed my theology. It not only articulates so well the idea that God shares in our emotional experience (which may be the most valuable theological concept I have ever embraced) but details how a prophet shares in the emotional experience of God. It not only changed my theology, but also the way I approached God in my personal life. Heschel is my favorite theologian, and this may be my favorite theology book.
7) God the Economist by M. Douglas Meeks
While I had already caught on to the idea that God has radical economic insights for us before reading this book, Meeks wrote down not only what I had been sensing, but also what I needed to read in a systematic way. If I were to recommend only one book detailing a Christian approach to economics, it would without a doubt be this one.
8) The Myth of a Christian Nation by Greg Boyd
While I have strayed slightly from the Christianarchist views that Boyd espouses in this book, it is still well worth being on this list. I was for so long upset with the current state of Christian political thinking, and Boyd said everything I was thinking and more. Every Christian concerned with politics should first read this. Boyd is relentless in his insistence that we base our political thinking off of Jesus, and equally relentless when he details the radical assertions that that entails. Even if you don't agree with everything, Boyd has a message that most Christian Americans today need to hear. (It was also the book that inspired me to become a pacifist.)
9) Inspiration and Incarnation by Peter Enns
Along with helping me come to terms with how to think about Scripture and what to do with some of the problems that the Bible poses, Enns reintroduced me to my love for studying the Hebrew Bible. At the time, I had strayed far from Hebrew Bible studies and had become only interested in theology, even planning to one day write a systematic theology (a notion I now think to be ridiculous). I was growing disinfatuated with theological discussions before I read this and when I did I realized once again how much I love studying the Hebrew Bible. This definitely isn't the best thing that could be said about Enns' work, as his thoughts on the Bible offer so much insight, but this is the most significant way that the book affected my life at the time.
10) The Art of Biblical Poetry by Robert Alter
I read this in my Psalms class and, at the risk of sounding repetitive and dramatic, it changed the way I read the Bible. It opened me up to the possibility of the literary analysis of the biblical text. Alter offers what was a profound insight to me at the time: the Bible is literature, beautiful literature, and it should be respected as such. I didn't learn growing up that I could analyze a passage in the Bible the same way one analyses a William Blake poem; it was Alter who introduced me to that notion, and I am quite thankful for that.
11) You Are Special by Max Lucado
This was perhaps the first book that profoundly affected my life. It was definitely the first one to make me cry (it sometimes still does). As a kid, I would read this and feel the truth of the statement as if I was hearing from God (and I think I was!): "You Are Special." It's a beautiful story with a message that impacted me as a kid in the greatest possible way. I highly doubt I'd be who I am today without it. In fact, I wouldn't be who I am today without any of these books. So, you should read them. They're amazing.