I just finished "Unchristian; What a New Generation Really Thinks About Christianity," by David Kinnaman and Gabe Lyons. Every church leader should read this book. If you read Dan Kimball's "They Like Jesus But Not The Church," you will see the same themes, except, Unchristian backs everything up with extensive, detailed survey research.
One of our Adult Education classes studied this book for a few weeks. It was very helpful. The class was quite incredulous about the results of national surveys which were rather eye-opening. I would suggest to those who might use this book in a class, to read it first...it's not entirely objective, as if anything is....but you might want to get a handle on its particular slant before using it as a resource.