I AM ONE OF THOSE PEOPLE who think out loud, trying out ideas as I hear them come out of my mouth. That means that my trusted colleagues and my closest friends are often the unfortunate ones who have to hear the untested theories and half-baked ideas that will never get published. I want to thank them for their patience and for their honest feedback in conversation. In terms of the present book, I especially want to thank some of those colleagues who are also friends, including Mike Aquilina, Charlie Cosgrove, and Stephanie VanSlyke. Your feedback and conversations about this book were very much appreciated. I also want to thank Dan Reid and everyone at InterVarsity Press for making me feel welcome in the IVP family.