This is one of the most refreshing and engaging books on church/culture that I've read, and is probably THE best book I've read from a leader in the emerging church.
Driscoll contends that as believers we must be concerned about three things: the gospel, the church, and the culture. When we neglect one of these three elements, we fall into one of three errors:
The Church + The Culture - The Gospel = Liberalism
The Church + The Gospel - The Culture = Fundamentalism
The Gospel + The Culture - The Church = Parachurch
I think this is slightly reductionistic, but it still provokes reflection. Driscoll's book is a plea for the church to be faithful to the gospel within the culture - not by isolating itself from the culture. He says, of course, that faithfulness to the gospel involves some measure of separation. As Christians, we are different - called out of darkness into light - and this will affect our life-styles and ethics. But Driscoll also contends that Christian liberty must be maintained in areas where Scripture is silent - and that our liberty should be used for the sake of reaching culture.
Of course, culture looks different in Seattle than it does in the Midwest, where I minister. Driscoll's church looks different than ours, with lots of tattooed, pierced, young Christians decked out in Gothic clothing and make-up! But Driscoll rightly argues that becoming a Christian doesn't necessitate a conversion to wearing business attire (like a middle-class, white suburban American Christian), but rather a conversion to Christ and His kingdom. As I said, this is a thought-provoking book.
Be warned, however: reading this book will probably provoke a variety of deep and intense emotional responses, including laughter (Driscoll is hilarious), shock (Driscoll breaks all the conventions that you would expect of a Christian author), and (hopefully) excitement, as you hear of what God has done in his life and through his life and ministry in the lives of others.