Laika
I understand your opinion. But the concept of the book is to help people to undestand that faith is unreliable to find the truth. It's not about preaching or debating, it's about reasoning until the person admits she doesn't know the answer for everything.
The goal is not search religious people and argue with them, but to use the method whenever a conversation with a faithful person (religious or not, some bielieve in pseudo-science) occurs. This method is very helpful for people like me who still has all family in the org (parents, grandparents, wife, in laws). Many oportunities to employ the method show up everyday, and I'm finding it the best tool ever.