My personal favorite nonfiction author. Wrote Losing Faith In Faith, one of the best books on atheism I've ever encountered. Dan Barker is an ex-fundamentalist, which gives him an extra perspective on Christianity that many atheist writers lack. His book details his conversion (or should it be deconversion?) from devout Christian to one of America's preeminent freethinkers.

He has appeared on the Oprah Winfrey show on many occasions as the "token atheist".

He is currently the Public Relations Director of the Freedom From Religion Foundation (http://www.ffrf.org).