A letter written by Cardinal Joseph Ratzinger, before he was elected Pope in April, condemns the boy wizard as a potentially corrupting influence on children.

The Cardinal, then the late Pope John Paul II’s “enforcer” as Prefect of the Congregation for the Doctrine of the Faith, revealed his views in a letter to the author of Harry Potter — Good or Evil?, a book published in Germany. The Cardinal appeared to sympathise with Gabriele Kuby’s thesis that Harry Potter corrupts the young, distorting their understanding of the battle between good and evil. “It is good that you enlighten people about Harry Potter because those are subtle seductions, which act unnoticed and by this deeply distort Christianity in the soul before it can grow properly,” he wrote.

The Cardinal, who had been sent the book by Kuby, encouraged the writer to send her work to another member of the Church who had made an announcement on behalf of the Vatican praising J. K. Rowling’s books. Mgr Peter Fleetwood, a British priest who helped to draft an official document on New Age phenomena in 2003, said that the Harry Potter books were moral stories that taught children about the importance of making sacrifices to overcome evil.

“I don’t think that any of us grew up without the imaginary world of fairies, magicians, angels and witches,” he told a conference at the Vatican. “They are not bad or a banner for anti-Christian ideology.” Rowling, he said, was Christian by conviction and in the way she wrote.

Austen Ivereigh, a spokesman for Cardinal Cormac Murphy O’ Connor, the Archbishop of Westminster, said that the Pope’s comments were strongly worded but that Catholics were not bound by them.

“This was evidently Cardinal Ratzinger’s view when he wrote that letter,” he said. “As Prefect of the Congregation for the Doctrine of the Faith he never issued an authoritative document on the subject so there is no question of Catholics . . . needing to take a single view. Personally I think they are a great read.” Harry Potter has a history of upsetting Christians. A pastor in New Mexico included the stories in a book-burning ceremony. Jack Brock, a priest from the Christ Community Church, said: “God says in Deuteronomy that witchcraft is an abomination. Whatever God hates, I hate.”

Explore Books

• Book Extracts

• Book Reviews

• Books Group

• Audio Books

Times Recommends

• 10 things you should avoid in hospital (unless there really is no option)
• Exclusive: Philip Pullman's essential reading list
• The White War by Mark Thompson