Barker, who no longer works to save souls but instead wages legal battles against perceived conflicts between the church and state, such as the national motto "In God We Trust" on U.S. currency and efforts to ban city councils from holding a prayer before meetings, recently spoke with The Christian Post about his evangelical past.

In his book, Godless: How An Evangelical Preacher Became One of America's Leading Atheists, Barker describes his journey in detail, but told CP that most of his "movement from firm born-again Bible believing evangelical conservative Christian to atheist happened within Christianity."

Barker adamantly told CP that he "didn't just jump from 'oh, I have a doubt, now I'm an atheist,'" because he believes no Christian does that. But rather, he sees believers as shuffling "back-and-forth, one way or another, across a huge vast spectrum of Christian theology."

"My migration, which took four or five years, started out as extreme far right side and then gradually moved across, where in the beginning, I didn't think, 'oh, these doubts are going to lead to atheism.' I thought they were strengthening my faith; and becoming less of a binary brain, absolutistic fundamentalist and more of a moderate, more subtle," Barker explained.