Why is it so vital that America's children be entertained by the likes of Harry Potter? There's plenty of adventure in the Bible. I am a devout Christian and my gut feeling is that Harry Potter is yet another device to enable Satan to get his filthy foot in the door. Is it any wonder that this nation is under such ruthless attack? What are we feeding our children's mind and souls with? I tell you: Alternate lifestyles, evolution and now sorcery and witchcraft. I'd advise you to seek the guidance of the Holy Spirit if you are indeed a real Christian and ask God to reveal the truth about Harry Potter. He has to me and I say that this literature is of a demonic nature and should not be assimilated by any child.
I respect your opinion and the right (and responsibility) you have to make choices for your family.
However, one of the things we do at Probe Ministries is to "engage the culture." That means interacting with issues and topics in our culture and examining them from a Christian world view. Some parents--MANY parents--do not have children who accept their "no" the way yours might, and will need to confront the Harry Potter phenomenon head-on. For example, dads of kids with a custodial mom who buys the books for them regardless of what the dad wants. If we can help people to find a way to use this major cultural icon to teach Christian truth, to find what is good in a major literary and now film genre and help them understand spiritual truth through it, then that's what we're called to do. Even if other Christians don't understand or agree.
I assure you that I have sought the guidance of the Holy Spirit; we would be foolish to do what we do here at Probe without His wisdom and guidance! I believe this falls under the category of "disputable matters." That means the Lord can lead you to avoid Harry Potter books and He can allow others to read them without sinning, and He still remains Lord and God.
By the way, the last time I checked, the test of a "real Christian" was the presence of the indwelling Christ as a result of trusting Him for life and salvation, not one's position on Harry Potter.