He has played God - twice - and beginning at 9 p.m. Sunday, he will lead National Geographic Channel viewers on a globe-spanning search for The Story of God, but don't, whatever you do, call Morgan Freeman an expert.

"I'm nowhere near an expert on anything, except, maybe, me," Freeman said in an interview in January.

Still, the Oscar-winning actor's curiosity had already led him to some big questions as host and narrator of the Science Channel's Through the Wormhole, whose first episode, six seasons ago, asked, "Is There a Creator?"

"These are areas that I find extremely interesting to explore . . . questions about the universe that include the existence of God," said the 78-year-old Freeman, whose company, Revelations Entertainment, produces both shows.

"They are inseparable subjects, you know. If you think about one, you have to think about the other. Particularly if you think about the universe," Freeman said, "you have to think about God."

Though he's still not an expert, "I'm conversant" in such areas, he said, and more so for "having taken this trip, having had these conversations with these extremely learned and dedicated people. I've learned an awful lot."

Freeman's respectful, inquisitive conversations form the backbone of a metaphysical travelogue that took the actor from his native Mississippi to far-off places like Egypt, India, and Israel to explore people's beliefs.

It also brought him to Philadelphia.

In the April 17 episode, Freeman not only speaks with Andrew Newberg, director of research at the Myrna Brind Center for Integrative Medicine at Thomas Jefferson University Hospital, but he actually lets the physician scan his brain for evidence of belief in God.

And not the deity he portrayed in the comedies Bruce Almighty and Evan Almighty.

"This has nothing to do with acting at all," Freeman said.

"I'm not one of those actors who goes off to do research to play a part. The only time I have ever done research to play a part was if I was playing a live person, or a person who you know. Then you have to find out about them . . . and maybe have to learn how to sound like them or look like them or walk like them or whatever," he said. "This kind of research is presentational. It isn't for me to become a Buddhist monk."

Among the things he learned from The Story of God: that reincarnation, to Hindus, isn't an end in itself.

"We learn that the Hindus believe in reincarnation. Stop. Period. But that's not all there is to it. They believe in reincarnation merely as a way to reach nirvana, enlightenment, oneness with . . . the universe," Freeman said.

"Reincarnation is a chore. It's not a prize. It's something they have to go through until they get it right."