Hallowe'en or Fall Festivals or Harvest Festivals

Every year in some parts of the country schools and churches have some kind of party, often with costumes being worn by participants.  In some communities, especially those with fundamentalist undercurrents, there is lively debate about whether it is Christian to celebrate Hallowe'en, or it's some kind of pagan festival.  And some schools and churches kowtow to these complaining, indicating a confluence of bluenosedness and/or cojone deficiencies. 

What's wrong with an old-fashioned Hallowe'en?

Okay, I can see where it might not be prudent to go to a fundamentalist-named Fall Festival while being dressed as a hot witch; but would it hurt to go as a hot nurse or a hot French maid?