The author is Joel Grus and the link to the book is here. I am a pro-religion non-believer, but if you wish to hear from an anti-religion non-believer, this is the place to go. He will tell you that your religion is false.
In addition to its humor, I prefer the content of this book to the better-known "new atheist" tracts. Grus yields many of the strongest arguments. For instance the biographical and sociological correlates with belief (most people choose the religion they grew up with, or encountered through a friend, etc.) suggest that, in this area, intuitions which feel "certain" simply cannot be trusted.