London, England - "The Da Vinci Code" has undermined faith in the Roman Catholic Church and badly damaged its credibility, a survey of British readers of Dan Brown's bestseller showed on Tuesday.
People are now twice as likely to believe Jesus Christ fathered children after reading the Dan Brown blockbuster and four times as likely to think the conservative Catholic group Opus Dei is a murderous sect.
"An alarming number of people take its spurious claims very seriously indeed," said Austin Ivereigh, press secretary to Britain's top Catholic prelate Cardinal Cormac Murphy-O'Connor.
"Our poll shows that for many, many people the Da Vinci Code is not just entertainment," Ivereigh added.
He heads a prominent group of English Roman Catholic monks, theologians, nuns and members of Opus Dei, who commissioned the survey from leading pollster Opinion Research Business (ORB) and have sought to promote Catholic beliefs at a time when the film's release has provoked a storm of controversy.
ORB interviewed more than 1,000 adults last weekend, finding that 60 percent believed Jesus had children by Mary Magdalene -- a possibility raised by the book -- compared with just 30 percent of those who had not read the book.
The English group demanded that the "Da Vinci Code" movie, being given its world premiere at the Cannes Film festival on Wednesday, should carry a "health warning."
The group, which stopped short of following the
Vatican line of calling on Catholics to boycott the film, accused Brown of dishonest marketing based on peddling fiction as fact.
The novel, which has sold over 40 million copies, also depicts Opus Dei as a ruthless Machiavellian organization whose members resort to murder to keep the Church's secrets.
The survey underlined the astonishing popularity of Brown's novel -- it has been read by more than one in five adults of all ages in Britain.
Ivereigh complained that Brown and film studio Sony Pictures "have encouraged people to take it seriously while hiding behind the claim that it is fiction.
"Our poll shows they should take responsibility for their dishonesty and issue a health warning."
In the survey, readers were asked if Opus Dei had ever carried out a murder. Seventeen percent of readers believe it had, compared with just four percent of non-readers.
Opus Dei spokesman Jack Valero said he was astonished.
"Since we were founded in 1928, Opus Dei has promoted the highest moral standards at work, spreading a message of Christian love and understanding," he said.
"Yet the Da Vinci Code has persuaded hundreds of thousands of people that we have blood on our hands."