Well, that's the rub, isn't it? The problem are the church ladies who see evil where none exists, such as the Harry Potter stories or Disney movies.
Very often, critics like O'Brien are simply suffering from professional jealousy.
The problem is those that seek to persuade others that evil, the occult, and demons do not exist and that they are the stuff of harmless fantasy, especially when those individuals claim to represent The Church.
When it comes to protecting one's soul, or that of one's child you had best be sure that what you expose it to is not harmful. If there is the smallest doubt that it is not good and pleasing to the Lord, it should be rejected. There is little room for error, for the stakes are eternal.
"There are two equal and opposite errors into which our race can fall about the devils. One is to disbelieve in their existence. The other is to believe, and to feel an excessive and unhealthy interest in them. They themselves are equally pleased with both errors and hail a materialist or a magician with the same delight." - CS Lewis