"seems very biased"
The author seems to write with an end in mind, rather than letting the stories tell how it really was. I am neither liberal nor conservative, but this book seems to come off very strong in the message of dividing church and state, and also ensuring tolerance. In order to make his point, he portrays a history where almost no one agreed with each other in their view of God nor religion. Therefore, everyone should keep religion private and tolerate everyone. I personally do believe that religion should not be mandated in schools, but I think there should be a healthy (and yes, optional) acknowledgement that reverence to God is part of our history.
The author seems to go almost too much overboard in portraying a one-sided view of how history was almost disastrous because of various historical figures and their public belief in God. I am no history buff, but I can tell a slanted story when I hear one...
Otherwise, the book was decent and interesting. However, the stories don't "flow" so well.
"highly recommended"
Not only is this stuff interesting, it really works. I tested this with some of my friends in guessing various things, like the number of steps from point a to point b. Just amazing... A great lesson about the value of the crowd's wisdom vs. the traditional view of glorifying experts.