I am part of Dr. Jim Spiegel's blog book tour which started a while ago, and you will be able to read my 3 part review of his book on 1-3 April 2010.
Preachers Who Don't Believe--The Scandal of Apostate Pastors. Dr. Mohler writes about the many preachers from different denominations that no longer believe in the Bible or in the existence of God.
One thing about Dr. Spiegel's book is that in it he writes on the issue of immorality driving atheism. The more a person gets into sin, the less likely he is to want to believe in God. In fact, some atheists have actually said that they hope that their is no God. Sin's motivation is to hide from God. That is how it started in the garden of Eden when Adam hid from God after he sinned.
It would be interesting to know how much these preachers' rebellion against God is driving their atheism.