Although he may be best remembered today as the author of the famed "Serenity Prayer," Reinhold Niebuhr — an outspoken American-born pastor, writer, and political activist — remains one of the most influential public theologians of our time. Presidents from Barack Obama to Jimmy Carter have credited his impact on their thinking, as well as John McCain, countless historians, theologians, political thinkers, and Dr. Martin Luther King, Jr., who cited Niebuhr in his "Letter from a Birmingham Jail."

Niebuhr's career spanned some of the most tumultuous decades in American history, from World War I through Vietnam, from the Great Depression through the Civil Rights Movement. An early pacifist and socialist, he was closely monitored by J. Edgar Hoover's FBI throughout his life, but would later serve as a consultant to the State Department during the Cold War.

Niebuhr rose from a small Midwest church pulpit to become the nation's moral voice — an American conscience — during some of the most defining moments in recent history. His books, Moral Man and Immoral Society (1932), The Nature and Destiny of Man (1941–43) and The Irony of American History (1952), continue to influence theological and political thinking. An American original, his unique insights into human nature and its relationship to political movements and social justice propelled him to speak openly, and often critically, to an America consumed by moral certainty. For Niebuhr the priority was always justice, his guiding principle was hope in a redeemer God, and his weapon was an extraordinary gift for clarity of thought that made him a leading voice of conscience for his time.

An American Conscience: The Reinhold Niebuhr Story is directed, written and narrated by Martin Doblmeier (CHAPLAINS), the creator of dozens of provocative, award-winning films on faith including Chaplains and Bonhoeffer. Rich in archival material, the documentary features interviews with former President Jimmy Carter, Cornel West, Andrew Young, David Brooks, Susannah Heschel and a host of internationally recognized historians and theologians.

PHOTOS: