Can anyone look at the world objectively? According to this author, no, definitely not. Working from that assumption (which I happen to agree with), he proceeds to deconstruct the deconstructionists, proving that all people base their worldview on certain unproved (and unprovable) assumptions. The skeptics who like to bash religion for being irrational and unscientific are not exactly the gold standard for rationality themselves.
I doubt the book would change the beliefs of the hardcore theophobes, since their biggest beef against God is that they don't like competition, plus they enjoy feeling intellectually superior to everyone else. I do think the book serves the admirable purpose of strengthening the faith of the faithful, much as C. S. Lewis's books Miracles and The Problem of Pain do. I read this book in 2009, and recently re-read it after witnessing the kerfuffle over Year of Biblical Womanhood and its author's emphasis on believing in a God she is "comfortable" with, which apparently struck a chord with a lot of ex-evangelicals. Timothy Keller, by contrast, is content to take the God of the Bible "as is," knowing that that God isn't some adorable spiritual pet that 21st-century "spiritual but not religious" people can cuddle with on a rainy day. Keller has a very high opinion of God, and a very low opinion of the human ego - in other words, he has the right priorities.
Rather than drag out the review, I'll let the author speak for himself:
All doubts, however skeptical and cynical they may seem, are really a set of alternate beliefs.
God's grace does not come to those who morally outperform others, but to those who admit their failure to perform and who acknowledge their need for a Savior. p 19
Any community that did not hold its members accountable for specific beliefs and practices would have no corporate identity and would not really be a community at all. p 40
When the idea of God is gone, a society will transcendentalize something else, some other concept, in order to appear morally and spiritually superior. p 55
Because Christians think wrongdoing has infinitely more long-term consequences than secular people do, does that mean they are somehow narrower? p 81
And, these two gems directed at the half-Christians or "spiritual but not religious crowd":
To stay away from Christianity because parts of the Bible's teaching is offensive to you assumes that if there is a God he wouldn't have any views that upset you. p 112
If you don't trust the Bible enough to let it challenge and correct your thinking, how could you ever have a personal relationship with God? In any truly personal relationship, the other person has to be able to contradict you. . . . You'll have a Stepford God, a God essentially of your own making, and not a God with whom you can have genuine interaction. p 114
I highly recommend the book for any Christian who feels uncomfortable about sharing his faith with his nonreligious friends, who is guilty of sharing the secular culture's contempt for Christians and their "irrationality" and "intolerance" and "exclusivism." If you ever feel the urge to ditch the label "Christian" and start calling yourself "spiritual but not religious," this book might well help you maintain your loyalty to the God revealed in the Bible.
Yes, as another reviewer stated - "not for the average reader". Keller is in NYC and encounters a more diverse audience. So he addresses several questions that secularists raise. He answers well, but you must slow down as you take in the information. If you are looking to deepen your understanding of reasoning with the secular world, this book is for you. I love the challenging read!