Friedman wonders how you can really ever know, since being an atheist or agnostic is political suicide.
I totally agree. In fact, I'd be willing to bet that the majority of people who voted for Obama believed that he was not actually a Christian (in the sense of believing the metaphysics of the religion, as opposed to merely being philosophically sympathetic to the teachings of Jesus), despite the fact that he attended church and practiced the customs of the religion.