I think Philip is missing the point a bit, with regards to the "big four" Atheism books... in order to attract people away from their entrenched religious beliefs into your arguably more enlightened humanistic worldview, you need to do two things:

1. Extol the virtues of humanism.
2. Point out the inadequacies of their incumbent views.

Clearly, the latter has to be done first with the former waiting in the wings to charge in at the right moment. There would be no point speaking at length about the wonders of humanism to a liberal Christian, if all they say at the end of it is "you sound happy, good for you. I'm happy too.". It's an ugly fact of life that you need to bring people down before you can help them back up. Nevertheless, I also think it is quite pointless to spend time angrily deconstructing someone's beliefs in front of then, only to walk away at the end without providing them with an alternative. We need books like Philip Kitcher's just as much as we need "shrill" critiques like The God Delusion.

People don't like to change their worldviews willy-nilly, especially if they are worldviews into which they have invested considerable effort and emotion... and people really don't like to admit when they are wrong.