I won't tell you you're going to hell, just because you've read Harry Potter, but I do disagree with some of what you're saying, and (respectfully) I'd like to debate some of it.
Where is God?First of all, doesn't the fact that there is no God in Harry Potter bother you? I mean, love and goodness and all that are great but when they don't point directly to God then He is not glorified. There are non-Christians all throughout this world that have love and are 'good' people, but if they don't believe in God they will go to hell, the Bible is very clear about this. Also, our biggest aim is to glorify God, not the good things that come from God. If we elevate love above God because it's a good thing that he gave us, then that's idolatry.
One more thing about God in HP. Not only is J.K. Rowling focusing the reader on the qualities of God's blessings instead of God, she is also being very prideful of the human race. By eliminating God, she is in effect stating that humans alone are good enough to solve problems, that they can do it on their own. This is a falsehood. There is no good in humans. We are completely and totally sinful. After the fall, we became sinful beings, to the core. It is only by God's grace that we are saved.
And you might ask me about the 'good people' who aren't believers and who aren't saved...why do they have such good, normal lives. The only answer I can give is the common grace which God gives all of us, but that is a very confusing concept that I haven't studied in-depth and I'm sort of going in over my head here; so I won't argue this point.
Magic is Not a Good ThingEdit: I did get into this in-depth, more so than the God part...but I feel strongly about it as you'll see. 
About the magic part. I'm not going to get into this in-depth, because I haven't read these books and I know less about magic then other people. But, I will venture a few claims that I think are solid. First of all, we both agree that there isn't a God in HP. We are agreed about this, because it is a fantasy world. But let's look at the Bible. What are the only places where you can see people doing 'magic' or miracles? In the New Testament, there's the disciples, and the false prophets. The disciples do this through the Holy Spirit. But the Holy Spirit is God. By your own reasoning, if the Holy Spirit is God, and there is no God in HP, then the magic in HP can not come from God.
What are the other assumptions that we can make. There are only two left: that it is either a human ability in HP or it is from the devil. But it is not a human ability, he learned it. Additionally, because humans are fallen and sinful, and there is no God in HP to redeem them, it stands to reason that the magic they practice will be flawed and not always used for the best reasons, unless they are perfect beings (and it is clear they are not).
One could make the argument that HP is a fantasy world, therefore maybe the humans aren't fallen, but it is clear throughout the books that the MC's make mistakes like everyone else. Because the books were written by a fallen human, they cannot capture perfection because we as 'real' humans are fallen, therefore we cannot envision (or write about) what a perfect human would look like.
So we are left with the assumption that it is a natural thing in their world, yet imperfect, or that it is directly from the devil (since there clearly is evil in HP, it's part of the story). I won't go into this, mainly because I haven't read the books, but I personally think that it might be a mix of both, subtly. But, like I said, I'm not one to go into this. But we have established that the magic is fallen, just like humans, and therefore is used for good only because of the common grace that God has given us.
Galations 5:19-20 wrote:
Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God.
Paul is very quick to call out the things that are not from god. We see impurity and jealousy and all these others as sin...why is magic a 'gray area' that Christians frequently gloss over?
Lastly, I will say that magic in any writing makes me uncomfortable. It's clear throughout the Bible that unless power is given through the Holy Spirit (as in the case of the apostles; which isn't even magic), it is given from the devil. Magic is basically power that the user does not normally have but is accessing. The frightening thing about magic is that it elevates ourselves and gives faith in ourselves. Instead of turning to God for help magic is sort of a 'back door', a way to elevate our own abilities, which is exactly why most magic comes from Satan. Just look at these verses from the Bible with me:
Ezekiel 13:18 wrote:
Thus says the Lord GOD: Woe to the women who sew magic bands upon all wrists, and make veils for the heads of persons of every stature, in the hunt for souls! Will you hunt down souls belonging to my people and keep your own souls alive?
Acts 8:9, 11 wrote:
But there was a man named Simon, who had previously practiced magic in the city and amazed the people of Samaria, saying that he himself was somebody great. [...] And they paid attention to him because for a long time he had amazed them with his magic.
This is exactly what I mean: magic exalts the user, not God.
Acts 19:19 wrote:
Also many of those who were now believers came, confessing and divulging their practices. And a number of those who had practiced magic arts brought their books together and burned them in the sight of all. And they counted the value of them and found it came to fifty thousand pieces of silver. So the word of the Lord continued to increase and prevail mightily.
These believers came and confessed their practices, which were clearly not worth keeping around.
2 Chronicles 33:6 wrote:
And he burned his sons as an offering in the Valley of the Son of Hinnom, and used fortune-telling and omens and sorcery, and dealt with mediums and with necromancers. He did much evil in the sight of the LORD, provoking him to anger.
The Lord was angry at this man's 'magic'. Again, I can't argue the books since I haven't read them (HP) but mediums, necromancers, it all sounds like HP to me.
Deuteronomy 18:10 wrote:
There shall not be found among you anyone who burns his son or his daughter as an offering, anyone who practices divination or tells fortunes or interprets omens, or a sorcerer
This verse goes so far as to condemn even 'innocent' magic such as fortune-telling.
Mark 5:3-4 wrote:
And when Jesus had stepped out of the boat, immediately there met him out of the tombs a man with an unclean spirit. He lived among the tombs. And no one could bind him anymore, not even with a chain, for he had often been bound with shackles and chains, but he wrenched the chains apart, and he broke the shackles in pieces. No one had the strength to subdue him.
In my mind, demon possession is equal to the magic. In humans, the only way 'magic' or 'sorcery' can be practiced is through demon possession. Both can augment the powers of the human. And both can oppress them.
Like I said, I haven't read the books, these things here are just things that have influenced me against reading Harry Potter and things that I believe in. And hopefully I didn't offend you, and no, I don't think you're going to hell for reading HP.

eruheran