Halloween is here, and for some religious people it is a very touchy subject. Some people, especially some Christians, think it's occultic and spiritually dangerous. Last year it was reported that the Vatican had condemned it, but that turned out to be slightly misinformed. A good essay on this written by Christian philosopher and apologist Kenneth Richard Samples goes over several common objections Christians have to Halloween, and correcting them: "The Tricky Topic of Halloween" (you'll have to scroll down a little). Ultimately, if someone still feels that celebrating Halloween violates their conscience and their devotion to their religion, then they should not participate in it. But we have an obligation to make sure that we've got the story straight and aren't just listening to one side of the issue. This is true of any subject.
Some people who have some anxiety about Halloween feel the same way about other things, such as the Harry Potter books and movies. I don't know anything about them, having never read the books, and only having seen the first movie on a plane with faulty earphones. I've seen books by Christians on both sides. Looking for God in Harry Potter and The Gospel According to Harry Potter obviously suggest that not only is there nothing to be concerned about, there is something to be encouraged. But others disagree.
I remember when I saw the movie Jumanji in the theater with a church group. I really enjoyed it and thought it incredibly imaginative. I was surprised when one member of the group said she almost walked out because of "occultic" elements she saw in it. Specifically, she thought it was reminiscent of ouija boards. I disagreed with this on several levels: first, the parallels between the game in Jumanji and ouija boards seemed very superficial. Second, at any rate, the movie clearly portrayed the game as something extremely dangerous that no one in their right mind would ever want to play. Third, I'm not really concerned about ouija boards because I strongly suspect that they're best explained as some subconscious response on the part of the participants rather than occultic forces, although I've never really investigated it in depth. Nevertheless, if one shows an interest in the occult, it can certainly open some dangerous doors regardless.
I've drifted away from the subject of Halloween, but you see the common thread here. I believe that there is a spiritual world, some of the elements of which are hostile to us. But I don't think this gives us a license to start seeing a demon behind every bush.