The issue of reality vs. fantasy is irrelevant. Fiction is a powerful conveyor of ideas; our culture constantly tells us this as it points out the power of myth and stories. The issue of how the book affects each child must also be considered with how these books have already affected the culture.
After the early success of Harry Potter, four publishers announced they would put out books with wizard or witch heroes for teens and preteens. One account relates, "Scholastic publisher and editor in chief Jean Feiwel said the new series have merely tapped into an increased teen interest in witches. 'It's almost gotten - dare I say it - acceptable,' Feiwel said. There's no doubt that fantasy and wizards have become more popular because of Harry Potter'" (Pittsburgh Post-Gazette, 8/8/01).
If one goes to the Scholastic website (Scholastic publishes the Harry Potter books in the U.S.) and looks up their series, T*witches, about teen witches, you can find an invitation to send in spells to keep the "spellbook" going. The spellbook page organizes spells into various categories, including: moon spells, homework spells, love spells, protection spells, summer bliss spells, etc. The spells reveal poems to the goddess and spells calling on various forces of nature. Karsh's Magick Tips on the site gives advice on how to cast spells, including suggestions to "go outside and work with Mother Nature," and getting a book to learn about the properties of herbs for use in magick (the site uses an occult spelling for magick).
It is not that this book has nothing good in it, such as Dumbledore acknowledging to Harry that he cared more for Harry's happiness than for the truth, and so did not tell Harry about the important prophecy and why Voldemort had tried to kill Harry when he was a baby (838). Harry wants to protect his friends and offers to teach them skills to defend themselves against the Dark Arts. And Harry is brave in many confrontations with the villains.
But these and some other incidents are very tiny slivers of light in the otherwise wasteland of spells, lies, deception, death, grisly scenes, and occult practices. When put on a scale, the bad side of this book easily outweighs any of the good from a moral or Biblical view.
What should we expect when the main setting for the book is a wizard who is studying at a school where they teach spells, divination, magical potions, and other occult techniques, and whose mentor is a powerful wizard (practitioner of the occult)? The fact that it is fiction does not take away from the reality of the occult practices.
Harry, as the hero, should model behavior that we would want children to learn from or emulate. However, since Harry has no remorse and few consequences from lying and cheating, and since he does not seem to grow wiser in goodness, there is only amorality presented to the readers. Being brave and loyal to friends is admirable, but these qualities by themselves are not moral since anyone – good or bad -- can be brave and loyal.
Harry is supposedly on the side of good, but what is that good based on? It can't be based on anyone's morality because none of the characters present a strong moral character. Is the good based on using magic for good? That begs the question of what good is, not to mention that using magick for good is wrong in God's eyes. So what is good according to Harry Potter? Is it just that good is less bad than an extreme evil, like Voldemort or Umbridge? Almost anyone would look good next to them. This is goodness born of relativism, just as a robber could be called good when compared to a mass murderer, and a pickpocket could be called good compared to an armed robber.
Before we can say it's about good versus evil, we have to see what the good is and how it is defined. It is clear in this book, and in the others, that good is based on how things turn out -- the ends justify the means. This is a philosophy in which any action can be rationalized for what is perceived as a good or useful end. It is not about what is good so much as it is about what is expedient. Harry cannot be a good hero simply by being the hero; and skillful fighting with spells is neither admirable nor good.
The popularity of the Harry Potter books does not give them a pass, and the criticism for pointing out the flaws in these books is not a reason to keep silent.
Do not be overcome by evil, but overcome evil with good. Romans 12:21
See that no one repays anyone evil for evil, but always seek to do good to one another and to everyone. 1 Thessalonians 5:15