While Halloween has Pagan roots and even a few Christian ones that came later after they used the day to start their own tradition, Muslims still see it as a Pagan holiday and don't believe it is just innocent fun. They warn Muslims not to be tempted to join in. Yes, they find it offensive.
Sad because Halloween really is just innocent fun. Most don't care about the origins and just enjoy the "Americanized" holiday, which today is completely different than the original All Hallows Eve. It really is about fun, dressing up and eating candy. And no one will perish in purgatory because they put on a SpongeBob costume and collected a bag of candy. Some don't see it that way and believe that we are paying homage to the Pagans if we participate.
The churches I knew that held Fall Festivals on October 31 were in Florida. That was about 18 years ago. I thought nothing of it and hold the attitude of 'to each his own.' I have no idea what type of churches they were.
I do have some Jehovah Witness neighbors, who keep to themselves until it's time to hand out those pamphlets. Sorry, but that practice irritates me. At least they no longer knock on my door after quite a few years of getting no where.
Halloween is harmless as a tradition and the only dangers are a few weirdos out there who would hurt people, but they are dangerous year 'round. We've all heard the horror stories of razor blades in apples and other despicable acts. Some people are just insane and should be locked up.
Halloween, as practiced by most Americans for years, has no religious undertones. I think it's wrong to paint it as Pagan or devil worship and condemn it.
Some need to lighten up. I am just waiting for Muslim Halloween costumes to be outlawed or deemed as hate speech.
Halloween in Islam - Should Muslims Celebrate Halloween