Faith and politics

St. Paul, Minn. — Democratic presidential candidate Barack Obama spoke strongly against his former pastor Jeremiah Wright. Eminent theologian and author Martin Marty talks about religion and presidential candidates.

Marty has also just revised a history of Christianity that he first wrote 50 years ago, a process that he says taught him the lessons he should have learned long ago.

Martin Marty: Professor emeritus at the University of Chicago Divinity School. His most recent book is "The Christian World: A Global History."