(RNS) Why do we believe?

Is it a learned skill?

Or is it a gift, like faith or joy or grace?

Can we lose the ability to believe, or never have it to begin with, depending on the hand life deals us?

I’ve been ruminating on the nature of believing since watching and re-watching the new documentary film, “Believe: The Eddie Izzard Story.” The 90-minute film, released on DVD last month, deconstructs the career of comedian Eddie Izzard, a man who is, perhaps, the funniest person alive.

Izzard has been a favorite of mine for years. His seemingly-stream-of-consciousness ramblings on everything from jam to Jesus are infectiously funny and imminently smart. I’ve seen Izzard perform live and watched, I believe, everything he’s ever committed to film — from comedy stand-up and feature-film roles such as the voice of Reepicheep in “Prince Caspian” to his virtuoso turn in the (sadly) short-lived TV series “The Riches.”

He is, in a word, brilliant.

Izzard, who is a transvestite and often performs in women’s clothing and full makeup, first won my heart when I watched his 1999 stand-up film, “Dress to Kill.”

It was his mercilessly funny (and frighteningly astute) take on religion and faith that grabbed my attention and my funny bone.

JESUS: “Look Dad, I went down there, I taught `em to hang out, be groovy, drink a bit of wine, they split into different groups! You’ve got the Catholics, the Protestants, the Jesuits, the Methodists, the evangelicals, the free Presbyterians, the locked-up Presbyterians… the Quakers, the Bakers, the Candlestick Makers… The Mormons are from Mars, Dad, we’ve had that checked out.”

GOD (in the voice of James Mason): “And what does the Holy Ghost think of all this?”

JESUS: “Oh, he’s useless, Dad. Got a sheet over his head these days.”

God, in Izzard’s acts, is always Mason. (And Moses sounds like Sean Connery.)

While he maintains that he is an atheist, Izzard regularly draws on religious history and theology for comic effect. The spiritual, it seems to this fan, fascinates him. Even if he doesn’t believe.

Izzard’s “Believe” is different from all his other performances. Maybe that’s because it isn’t a performance. It’s real — a behind-the-scenes look at the comic’s struggle over several decades to achieve success. “Believe” paints a compelling — at turns hilarious and intensely moving — psycho-spiritual portrait of Eddie the artist.

In it, we learn how driven Eddie the man is. And, to an extent, why.

“You’ve got to believe you can be a standup before you can be a standup,” Izzard says. “You have to believe you can act before you can act. You have to believe you can be an astronaut before you can be an astronaut. You’ve got to believe.”

Izzard, 48, was born in Yemen, and raised in Northern Ireland and Southern Wales. His mother died of cancer when he was just 6 years old. He caught the bug to perform as a schoolboy, shortly after her death.

Unbelievably, almost fearlessly driven is how Izzard comes across in the documentary. He just wouldn’t give up until he made it. Big. He worked hard, made sacrifices and nonsensical leaps of faith to get where he is.

In a particularly poignant scene toward the end of the film, Izzard talks about why he strives so tirelessly.

“I think that performing was about trying to get everyone to love [me]. You’re trying to get the love of the audience, and that was the big swap from mom’s love not being there,” he says, choking back tears. “The big problem is that everything I do in life is trying to … uh … get her back. I think if I do enough things that maybe she … maybe she’ll come back.

“Yeah,” he croaks, “I think that’s what I’m doing.”

Izzard had to believe in himself. And the power of his believing earned him great success.

Still, that profound loss remains. Izzard keeps striving for more. To do more. Create more and better. To be more and better.

He is a generous man. Last summer, with just a few weeks’ training, Izzard ran more than 1,100 miles around the British Isles — the equivalent of 43 marathons in 51 days — to raise more than $300,000 for charity. It seemed like sheer will and a stubborn belief that he could do it because he said he would, kept him going.

As a fan of his work and an admirer of the man, I wonder whether some day all that hard-practiced believing and will-driven running might bring Izzard to the place where he can believe in the unconditional love of a God who knows and loves him — just as he is.

(Cathleen Falsani is the author of “Sin Boldly: A Field Guide for Grace” and the new book, “The Dude Abides: The Gospel According to the Coen Brothers.”)