Radical is a book to challenge you. It's about moving away from comfortable Christianity and being stretched - my goal for the recent mission trip I went on. "In our quest for the extraordinary, we often overlook the importance of the ordinary, and I'm proposing that a radical lifestyle actually begins with an extraordinary commitment to ordinary practices that have marked Christians who have affected the world throughout history" (pg. 193).
I read Radical last year. It stirred me up and made me want to do more than just go about life as usual. It's a book to read more than once. You can learn more about the book as well as download banners for the book and and chapter resources for the book.