I am going to put in a vote for The Hammer of God, by Bo Giertz.
When I first read The Hammer of God--almost 25 years ago now--it made a profound impact on my life. First, there was the Swedish connection: My grandparents came from Sweden--in fact, from the same diocese where Giertz served as bishop and where my cousins still live. Second, the book reflected my own personal journey: I had spent some years in the charismatic movement, so I could identify with the pastors in the stories who came to see the problems with similar "super-spirituality" movements. Third, Giertz was just a darn good writer, with real insight into human nature and pastoral theology and practice. Fourth, reading The Hammer of God inspired me to do more with my Swedish and with Giertz, and so I have spent a lot of time in Sweden and have translated a number of Giertz pieces into English. I plan to do more of that. Right now, it so happens, I am in Fort Wayne, taking a two-week continuing-education course on the life and work of Bishop Bo Giertz, taught by Dr. Rune Imberg of Sweden.