This article helpfully applies Scripture to the issue.
This is an area where different experiences are going to lead people to different conclusions about what they should do. If your neighbor is a witch with spooky stuff going on that's more than decorative, you'll tend toward one view. If all your Halloweens have been about Superman costumes, visiting Grandma's house, and getting candy, you'll tend another way. (I think a better alternative is to hold a Reformation Day party, by the way.)
Give each other a break on this one, people, okay?