ET goes one-on-one with Stephen Mansfield, author of the fascinating new book, The Faith of Barack Obama, which delves into the presidential hopeful and his religious views, which the author says play a major part in an election.

"Faith shapes their world view, shapes their politics, shapes their understanding of right and wrong, which is what politics is all about," Mansfield says.

The author says Obama could be the most religiously experienced candidate America has ever had.

"He's thinking it through and fashioning his own faith and surveys show that's what most people do in this generation."

The Faith of Barack Obama is in stores now.