Human beings can imagine things that are not real. For instance, nobody knows what Jesus Christ looked like, still we all have a mental image of him. Our imagination can create other worlds where reality is altered, e.g. where Superman can fly, Cinderella travels to the ball in a magic carriage made from a pumpkin, Merlin in "The Sword in the Stone" turns Arthur into a bird, and then into a fish. All of this is fantasy. Magic is a literary device often used to explain how these impossible things come about. Science fiction also tells about unreal things, but uses "future technology" to explain them. It's the same thing.
"Magic" can have at least three different meanings: it can refer to illusionist tricks, to occultists calling on spirits, or to a fictitious power that some people have in sagas and fairytales. All of these are different. When Harry Potter uses magic, he is not performing illusionist tricks. Nor is he calling on demons. He is using an inherent ability that some people have in the fantasy world of the books. It is no different from Superman's ability to fly or Luke Skywalker's ability to use "the Force". Harry Potter and his friends are special. Their ability to use magic is inherent and cannot be acquired. Nothing in these books encourages the reader to attempt it. The magic of these books is not the same thing as the magic of occultism.
Anti-potterists are saying that there can be no difference between reality and imagination. If you imagine something, it has a bearing on your beliefs about reality. This is clearly false. I can imagine a world where e.g. humans can breathe under water and walk around on the bottom of the sea as well as on land. This does not mean that I believe this to be real, or that I will throw myself into the local lake and drown. In fact, even children are able to differentiate between imagination and reality. Harry Potter will not make them believe that they have (or can get) magical powers. But they are still entertained and stimulated by fantasizing about magic.
It is the differences between fantasy and reality which make fantasy interesting. Swedish author Astrid Lindgren wrote several children's books about a character called "Pippi Longstockings", a girl of 9 years who is (among other things) so strong that she can lift a horse. Clearly, those books would have been utterly pointless if all children were that strong. It is the tension between reality and the fantasy world which makes it exciting.
Magic occurs in hundreds of other children's books, and has done so for centuries, without creating any wave of occultism. When confronted with this, anti-potterists reply that the Potter books are special because magic is their central theme. Everything revolves around magic and casting spells.
This is not true. Magic is part of the world where Harry Potter lives, just like spaceships and interstellar travel are part of the world in Star Wars -- or like horses and revolvers are part of the environment in every Wild West movie. That does not mean that spaceships or horses are the focus of the story. Rather, the Harry Potter books are about friendship, danger, adventure, growing up and learning to do what is right. The magic is just part of an exciting setting.
Anti-Potterists claim that the Potter books will turn children into witches, make them practitioners of occult arts and turn them against Christianity. But they have not been able to present us with a single example of that this has happened. Where are all those witch children?
Anti-potterism rests on pure speculation. This is an old and familiar thing. When cheap novels were first marketed to the broad public in the 19th century, alarmists warned that "sentimental women" would become so depressed by tragic love stories that they would commit suicide. When moving pictures arrived, alarmists warned that people would have their reality confused and go insane. In the 1980s, fundamentalists campaigned against role-playing games and claimed that youngsters who played would go insane, lose touch with reality, and commit suicide. NONE of these things have happened.
I meet hundreds of children in my work as a minister in the Church. Most of them have read Harry Potter (or had the books read to them by their parents). NOT ONE of all those I've talked to has ever expressed any interest in occultism. When asked if they believe that magic works "for real" they all answer "certainly not!" and look at me as if I was nuts. Further, the first book was published in 1997. Yet after seven years, there is still no evidence of increased membership in occult or magic-practising groups. This, at least, proves that the anti-potterist's warnings and predictions were simply wrong.
Confronted with the utter absence of young occult practitioners, some anti-potterists instead claim that the Potter books are part of satanic activities designed to "prepare the young for the coming of the Antichrist". By familiarizing children with occult symbols, ideas and practices, and depicting them as good and desirable, the books will make them more prepared to accept the rule of Antichrist.
But the books do not actually familiarize children with any of these things. Real occult ideas are hardly present here, and when they are -- such as in Divination class at Hogwarts -- they are ridiculed. Flying on a broomstick or opening doors by the wave of a magic wand is very far from the sort of thinking you find in books by real occultists. Also, it is unclear in what way the Antichrist would benefit from books where truth and loyalty are important values and where the evil people are always those who misuse their abilities to gain power over others.
I venture to claim the absolute opposite. Look at "The Order of the Phoenix". It contains a vivid image of the mechanisms of oppression, how people are manipulated, frightened and/or seduced to support injustice and tyranny. If anything, it should prepare us to see and resist the machinations of the Antichrist.