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Does God exist? What are the odds?
Isn't the divine purely the purview of faith? No multiplication required?

Yes and no, Stephen Unwin, this very nice, surprisingly funny and extremely patient physicist, was explaining to me the other day.

Unwin, 47, is the author of the aforementioned book, The Probability of God: A Simple Calculation That Proves the Ultimate Truth. He's originally from Manchester, England, and was a technical attache to the U.S. Energy Department before becoming a risk analyst for things like nuclear power plants, and then turning his expertise on the Almighty.

"I don't consider anything to be understood until numbers have been applied," Unwin said as I sat blinking silently on the other end of the phone one day last week. "Maybe that's just my bias, but that was the only way I could go about at least convincing myself."

Not me. Numbers bad.

"I understand that. My thinking was, I mean, that was very much the conclusion of what I did, that the faith part is not based on the reasoned assessment of the divine," he said. "I've always been very curious that some people are 100 percent certain that God exists and others are 100 percent certain that he doesn't, and yet we're all confronted with the same types of evidence."

Unwin didn't set out to answer in a deterministic, yes-or-no way the question of whether there is a God.

He just wanted to know what the odds were.

It's a compulsion surely Blaise Pascal, the 17th century French philosopher and mathematician, would understand. Pascal, in his famous "Wager," said, basically, it makes more sense to believe in the existence of a God because if you do, and there is no God, you lose nothing. But if you don't, and God does exist, you could be in deep doo-doo in the afterlife.

Is it audacious to think that the existence of a personal God -- and that is the definition of "God" that Unwin used, as opposed to a pantheistic idea of deity -- could be quantified in a number?

Not if you consider, as Unwin does, that every occurrence involves probability.

"Do you realize that there is some probability that before you complete this sentence, you will be hoofed insensible by a wayward, miniature Mediterranean ass?" he writes in the first line of Probability of God. (That's got to be the best opening line I've read recently outside of a Tom Robbins novel.)

But how do you figure the odds on God? You take Pascal's Wager and apply something called Bayes' Theorem.

Thomas Bayes was a Presbyterian minister in the early 1700s who had more than a passing interest in mathematics. His theorem, which is complicated -- I don't even think my keyboard has the capability of reproducing it, frankly, even if I were so inclined -- figures the relative likelihood that certain evidence will be produced if God exists or doesn't exist.

Starting with the assumption that the probability of whether God exists is a coin toss -- a 50-50 chance -- Unwin uses Bayes' Theorem and six areas of "evidence" to modify the probability.

(If your eyes are glazing over, keep reading. I'm about to wind this math business up. Promise.)

Each of the six areas of evidence -- including "the recognition of goodness," "the existence of evil" and "religious experience" -- is assigned a numeric value (through another mathematical equation I don't understand) and is applied to the original 50 percent, to produce the probability that God exists.

Which is 67 percent, apparently....