It was one of the big Catholic stories of 2006, but the key question hadn’t occurred to me until I knew the answer.

Is Dan Brown a convinced heretic hell-bent on bringing down Christianity or a dime-store novelist who stumbled on a crackpot conspiracy theory on par with alien abductions, Holocaust denial and lizard men?

I was sitting at lunch in New York City’s Olde Towne bar with a friend from the book world — someone who’s advising me on one of the future titles in my Bad Catholic’s series for Crossroad Publishing. We chewed clam strips and drank pints of Blue Point, leisurely batting back and forth ideas for yet more titles. At one point, I muttered something about Dan Brown’s The Da Vinci Code as a piece of hate literature, on par with those anti-Semitic conspiracy books sold by Black Muslims on Times Square. I little suspected that my lunch partner knew Dan Brown.

“In its day,” I started ranting, “The Protocols of the Elders of Zion was taken seriously.”

The Times of London in 1921 was concerned enough to assign a reporter to investigate whether or not the Jewish faith really was an elaborate conspiracy to dominate the world. Needless to say, The Times discovered that the book was a hateful forgery — but it’s telling that the paper felt the need to look into it. Thus the power of cleverly crafted fiction.

I expected my companion — let’s call him “Ted”— to agree with me. He’s a church-going Protestant, and he knows the basic plot of Brown’s potboiler: that the Christian faith is a centuries-old conspiracy to dupe believers, oppress women and dominate the world — which Dan Brown, an intrepid spy novelist, has uncovered and revealed to airport readers around the world.

Brown has claimed that it’s “fiction,” but based on “historical truth.” It has sent thousands of witless tourists on guided tours to France in search of “clues” to the “Templar mystery” — and convinced millions of readers that the respectable Catholic devotional group Opus Dei is a scary cult.

But Ted didn’t rise to the bait. He just shook his head.

“Dan Brown’s not anti-Christian. He’s not anti-anything. I doubt he’s pro-anything, either, except pro-Dan Brown. That book has as much of an agenda as The Complete Idiot’s Guide to Hockey. Dan Brown doesn’t have enough conviction to make a decent agnostic. He grew up a faculty brat in New England, and I don’t think he set foot off campus until he was in his 20s.”

I perked up, and ordered another beer. “You know Dan Brown?”

“I knew him for years. He started out as a joke-book author,” Ted said, dunking a clam-strip in tartar sauce. “Some of the jokes were funny. But he wanted to be a novelist. He kept pestering me about it, so finally I gave him this paperback, Writing the Blockbuster Novel, by Albert Zuckerman. It’s a paint-by-numbers guide on how to write a page-turner. One important part of the formula was: Find a villain your readers can safely hate. A few months later, Dan brought me this manuscript to read — and it followed the formula precisely … as if he’d poured Jell-o into a mold. In this case, the ‘safe villain’ was the National Security Agency, government spies. It sold pretty well, and he kept on pounding out books — each time with a different ‘safe villain.’ Eventually, he started running out — communism was gone, the Nazis were all dead. … That pretty much leaves the U.S. government, drug cartels and the Catholic Church.”

I was taken aback. “Do you mean to say that Dan Brown came up with this theory about the Church just to sell a few lousy books?”

Ted chuckled, ruefully. “Thirty million lousy books. I remember when he was working on it. We went to lunch with an editor. Dan started rattling off this conspiracy theory about the Church, then he got really nervous and turned to the editor, almost blushing. ‘Excuse me,’ Dan said to him. ‘You’re not Catholic, are you?’”

Ted downed his beer. “The editor was well known to be Jewish. That’s how much Dan Brown knows about religion.”

A thought-provoking lunch. It convinced me that it’s probably not worth protesting this silly, mercenary book — or the boring movie made of it by Richie Cunningham — I mean, Ron Howard. If you know someone gullible enough to take a pulp airport novel as “evidence” that Jesus Christ was not divine but just a man on a “hook-up” mission whose greatest achievement was a race of bumbling French kings. … Do you really think the answer is to argue with him? Using, you know, reason? You might just as well pick up the book, smack him on the nose and say “No! Bad! No! Very bad!” That’s likely to be more effective, and a heck of a lot more fun.

Well, that’s not entirely true. Admirable efforts such as Mark Shea’s and Amy Welborn’s to refute the assertions woven throughout the turgidly typed pages of The Da Vinci Code are doing a very good thing by teaching people about Christ, simply because, in his bumbling way, Dan Brown brought the subject up.

Or here’s another idea, which is even more entertaining. It’s a strategy I once used with a friend who was intelligent but emotionally unstable. At a dark time in his life, he got himself sucked into poisonous theories that questioned the Holocaust. Rather than spend time reading the sludge churned out by nostalgic Nazis that he was taking as Gospel, I decided to try what I called “ridicule therapy.”

When he suggested that the Holocaust had been exaggerated or faked, I said, “You’re so naive. Do you really think there was a so-called ‘Second World War?’ Another lie foisted on us by you-know-who ….”

“But that’s ridiculous,” he insisted.

“Really?” I said, “Or is that just what they want you to think?”

As time went on, I had to go further. So I suggested darkly that the Freemasons had been “faking the weather” for the past 30 years. I started referring to the “so-called weatherman” and putting little air-quotes around the word “weather.”

After a several-months barrage, my friend stopped reading Nazi trash. He’s a little embarrassed about the whole episode now, as well he should be. And no, he’s not a fan of The Da Vinci Code.

So if you know anyone tempted to believe in Dan Brown’s fairy tales, I suggest you buy him not just Amy Welborn, but several other conspiracy books. If he agrees, you really should warn him about the so-called “weather.”