In a letter dated March 7, 2003 Cardinal Ratzinger thanked Kuby for her "instructive" book Harry Potter - gut oder böse (Harry Potter- good or evil?), in which Kuby says the Potter books corrupt the hearts of the young, preventing them from developing a properly ordered sense of good and evil, thus harming their relationship with God while that relationship is still in its infancy.
"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," wrote Cardinal Ratzinger.
His Infallibleness obviously never got as far as chapter 37 of Order of the Phoenix, in which the parallels to certain aspects of Christianity smack one over the head. Bet he never read C.S. Lewis either.