How's this for starters?
Two thirds of Britons who have read Dan Brown's thriller believe that Jesus fathered a child with Mary Magdalene, a claim rejected as baseless by historians and Bible scholars.
Those who have read it are also four times as likely to think that the conservative Roman Catholic organisation Opus Dei, whose members include the Cabinet minister Ruth Kelly, is a murderous sect.
Seventeen per cent of readers are convinced that the lay group, whose founder was canonised by the late Pope John Paul II, has ordered or carried out a murder, compared with four per cent of those who have not read the book.
Yes, some people are in serious need of education, but it really isn't enough to say "tut-tut" and that's their problem. If you see someone walking around with her shoulder bag unzipped, contents showing, you don't just say "she's asking for it" do you?(Stumbled into this via Cafeteria is Closed, who found this through Open Book.)