The answer? It depends on the context of the film.
A number of witnesses in my cong absolutely refuse to watch Harry Potter. Some will even refuse to watch Lord of the Rings. But a few witnesses will watch Lord of the Rings, but they will keep quiet about it, because it is a "conscience matter" and they do not want to offend those that wouldn't watch it.
There are several similarities between Lord of the Rings and Harry Potter:
1) Both contains scenes of violence - Lord of the Rings contains more. (Think of all those ork battles you saw)
2) Both contain supernatural phenomena - Lord of the Rings has too many to mention, Harry Potter can cast spells
3) Lord of the Rings has a fire demon (part I) Harry Potter has wizardry
4) Harry Potter goes to a school for wizards - Lord of the Rings - there are a variety of magical acts performed by both wizards
So what's the difference?
Harry Potter is set in the "real world", Lord of the Rings is set in a "fantasy world"
According to some dubs consciences, if a movie is set in the "real everyday world in which we live" and contains supernatural events, hauntings for example, it is not suitable to watch. According to their logic, any supernatural events must be demonic and from Satan.
If a movie is set in a "fantasy world", then by definition, anything can happen, becuase it is a make believe world and is dissimilar to the world we live on.
Yet, what they fail to realize, is that both of these movies contain supernatural events, yet they will watch Lord of the Rings because it is of a fantasy genre, hence it must be OK.
Such logic...