Walk into any mega-chain bookstore these days and you're confronted by evidence of the Great Church Cover-up.

Front and center is the holy grail of conspiracy theories itself, "The Da Vinci Code." With 46 million copies in print — almost one for every six Americans — "Da Vinci" is still atop the best-seller lists and will bring the story to the big screen on Friday.

Then there are stacks of "Da Vinci" stepchildren, like "The Templar Legacy," "The Secret Supper," and "The Last Templar." You'll also find a fresh printing of 1982's "Holy Blood, Holy Grail," which earlier spun the modern image of Jesus Christ as family man.

Deeper in the store, near the Bibles, are a number of books disputing "The Da Vinci Code."

The public's unquenchable thirst for juicy alternatives to the "greatest story ever told" prompts the question: Why are so many people getting their church history from pulp fiction? The answer may be that even Christians — Roman Catholics, mainline Protestants, and evangelicals — haven't learned it anywhere else.

"I think the book does fill a void; this is a story and the churches have gotten away from storytelling," says David Turk, provost and vice president for academic affairs at the evangelical Alliance Theological Seminary in Nyack, N.Y. "People have a real need to know — not only 'did George Washington chop down the cherry tree?,' but what was Jesus' life like? We want to know, and the book raises questions that strike home. Churches can't run from it."

Dan Brown's book, a work of fiction that cleverly states it is based on real documents, offers theories that have riled much of the Christian world — that Christians saw Jesus as a mortal until a church council decided otherwise in the year 325, that the early church rejected "gospels" that humanized Jesus, and that Jesus married Mary Magdalene and had a daughter with her.

Even though virtually all Christian scholars insist that Brown's plot is nothing more than fantasy, many also understand why the book has become a phenomenon. So few people have been given a grounding in church history, they say, that "Da Vinci" seems intriguing, even plausible.