Summer's over, but Dan Brown's big beach read "The Da Vinci Code" - still a best seller six months after its publication - has just hit the 2 million mark.

Not all readers are fans of the Holy Grail murder mystery anymore.

Detractors are popping up. They find fault with the book's research, accusing it of intellectual dishonesty and calling it anti-Catholic.

Brown refuses to defend or even speak about his work, though he'll be here Sept.21 for New York Is Book Country.

The idea in the novel that the church conspired to conceal a lineage created by Jesus marrying Mary Magdalene and a celebration of "the sacred feminine" is criticized by Rev. James Martin, editor of America, a national Catholic weekly.

"Historically, the church has downplayed the contribution of women in early Christianity," he says. "But this book could give people the false notion that the church is sitting on secret gospels and whatnot, while all of it is out in the open."

The novel, which begins with a murder in Paris' Louvre museum, also implies there are still those willing to kill to keep church's secret.

Brown's editor, Jason Kaufman, says: "It's always been in the interest of certain organizations to portray themselves in a better light." But the critics include people with no organizational stake.

The novel "misdates the development of the doctrine of Christ's divinity" making it "an invention of the Roman emperor Constantine," says Sandra Miesel, a medievalist.

Also, she says, "though I can't address legal plagiarism, he borrows heavily" from two earlier works of amateur research, "The Templar Revelation: Secret Guardians of the True Identity of Christ" and "Holy Blood, Holy Grail," a speculative look into Jesus' bloodline. Both have been discredited by most scholars.

Similarities between "The Templar Revelation" and "The Da Vinci Code" include an interpretation of Leonardo da Vinci's "Last Supper" as depicting the figure to Jesus' right as Mary Magdalene rather than an effeminate John the Baptist, who is otherwise nowhere to be found.

Brown also incorrectly attributes the commission for "The Madonna of the Rocks" to a convent, and has da Vinci bombarded with Vatican commissions, while there was only one.

The book's hero cites the absence of a chalice from "The Last Supper" as proof da Vinci knew none was involved with the Grail. But, Miesel says, the painting is based on a line from the Gospel of St. John, which has "nothing about the institution of the Holy Eucharist."

For those up on papal history, a Pope tossing the ashes of the Knights Templars he has exterminated into the Tiber also defies logic, since that pontiff was then in exile in Avignon.

Such mistakes may not jump out at the lay reader. But the contention that the church burned 5 million witches at the stake does - and runs counter to contemporary scholarship, which places the number at closer to 50,000.

The Opus Dei monk who murders to protect the church, is said to operate out of a "$42 million, 133,000-square-foot World Headquarters on Lexington Avenue in New York City."

Opus Dei has no monks, no monks' robes. The building is "our American headquarters," says press contact Brian Finnerty.

Kaufman, though, stands by his author.

"Nothing is made up in Dan's research," he says. "He's a student of this stuff.

"This is a contemporary story, completely fictitious, but woven around a vast amount of research into buried history."

Copyright 2003 New York Daily News