I don't think it's likely to unconvert someone like your neighbour either, Charlie, but not because it isn't perfectly designed to do so. As Dawkins himself points out, he is the exact opposite to a fanatic in his measured and analytical approach to his subject.
The bottom line is if someone proved tomorrow that evolution was a false hypothesis and that God made us all afterall, Dawkins would accept he was wrong - that is the opposite of being a fanatic.
The faithful are, by definition, immovable in their faith - that is the essential tragedy of mankind. But the very anger your neighbour displayed at least suggests that Dawkins touched a nerve and so therefore is seen as a threat to religion - otherwise why get so angry? It's just someone else's opinion.
But I do think this book - and other such books - will make a difference slowly. But only to the already doubting. I honestly believe we have a finite future unless organised religion is put in its place as an anachronism and a danger. We fret about reusing plastic bags and wiping our bottoms with recycled loo paper, while the biggest danger to our future gets treated with kid gloves.
I have no problem with people having or developing a personal relationship with whatever they perceive God to be, but aligning yourself with these corrupt organisations and taking their man-made books as moral instruction manuals, has never shown itself to be a good idea and never will.
