Three "atheist" books have recently attracted a lot of attention. These are by Christopher Hitchens, Richard Dawkins, and Daniel Dennett. While all of these will appeal to atheists, none, I think, will much appeal to people of faith. The Hitchens book is filled with legitimate outrage, often humorous, but almost always cynical and negative. The fundamentalists of all religions already have answers to his facts, and the religious moderates will feel offended and compelled to try and fight back. No one is likely to contemplate their faith as a result of reading this book.
The Dawkins book I have not read, but from the reviews I have seen, it appears to be focused on disproving the existence of god, or at least on proving its improbability. This will never convert a theist, because the theist knows that god exists, and therefore knows that there must be flaws in all proofs to the contrary. This entire line of reasoning is as old as the hills, and, in my opinion is not one which is either necessary or useful.
The Dennett book is really of another sort altogether. It is not really an atheist book at all. It is actually an academic exploration of the roots and evolution of religion. It never comes right out and suggests that a person of faith might want to rethink this as a consequence of the insights in the book. So I don't think it really connects to anyone's personal belief system. Besides this, I think it is much too academic for most readers.