Former President Jimmy Carter recently celebrated his 100th birthday, the first former president to reach that milestone. While still controversial as a president, he is generally regarded as the most active and productive post-president in recent history, also the most religious. This week, Grant Reeher talks with Randall Balmer, a professor of religion at Dartmouth College, and a Carter biographer. He's the author of Redeemer: The Life of Jimmy Carter.