The Christian is not to be involved with or support the occult, witchcraft, demonism, or any other thing that uplifts the occult. To do so is to contradict God’s word, dabble in the demonic, and invite judgment from God. If a Halloween celebration is centered on demons, devils, spirits, etc., I would say don't have anything to do with it.
On the other hand, it isn't wrong to dress up in a costume and go door-to-door saying "Trick or Treat." Provided that the costume isn't demonic, I can't see anything wrong with this. It's just fun for the kids.
Take a look at the Christmas tree. It was originally an ancient fertility symbol. Yet, it has become a representation of Christmas and the place where gifts are placed. Are the Christians then paying homage to an ancient pagan fertility god? Not at all. They do not consider it pagan and are simply joining in a cultural event and giving no honor to anything unscriptural.
Think about this. In the Bible in 1 Cor. 10:23-33, Paul speaks about meat sacrificed to idols. This meat was often sold in the meat market; and the question arose, "Should a Christian each such meat?"
Paul said in verse 25, "Eat anything that is sold in the meat market, without asking questions for conscience' sake." This is most interesting. He says it is okay to eat the meat bought in the market place even though that meat may have been sacrificed to idols.
Then in verses 28-29 he says, "But if anyone should say to you, 'This is meat sacrificed to idols,' do not eat it, for the sake of the one who informed you, and for conscience' sake; 29 I mean not your own conscience, but the other man's; for why is my freedom judged by another's conscience?" (NASB). Paul is saying that if you find out the meat was sacrificed to idols, don't eat it--not because of you but because of the other person. In other words, eating that meat won't affect you. But, it may affect the attitude of another who does not understand the freedom the Christian has in Christ.
Is it any different with Halloween (or Christmas)? No. Even though Halloween has pagan origins and because of your freedom in Christ, you and/or your kids can dress up in costumes and go door-to-door and just have fun. However, if you are not comfortable with doing this, then you should not. If you know of a person who would be hindered by doing it, then you shouldn't either.