Below is a discussion I copied and pasted from Todd Wilson's website about trick or treating.  I wish I was so good about finding Bible verses to use in times like this:

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A friend of mine posted this on Facebook. She titled it "Halloween the king of oxymorons" It was to long to put the entire thing on here but I think you will get the just of the writing. I always like to line things up with what the Bible has to say. After all it is the best compass. Enjoy!

Woe to those who call evil good and good evil, who put darkness for light and light for darkness…”
Isaiah 5:20

We have called what is evil “good.” We know that there is nothing “happy” about Halloween. Yet, commercially speaking, Halloween is second only to Christmas. According to sales statistics alone, we’ve clearly made the darkness our light.

“Avoid every kind of evil.”
1 Thessalonians 5:22

God doesn’t tell us to avoid every kind of evil except the kind that seems fun or harmless to us. Evil is evil, no matter what commercial package it comes in. I once heard a friend say that you can slap some lipstick on a pig, but that doesn’t change the nature of the beast.

“For you were once darkness, but now you are light in the Lord. Live as children of light (for the fruit of the light consists in all goodness, righteousness and truth) and find out what pleases the Lord. Have nothing to do with the fruitless deeds of darkness, but rather expose them.”
Ephesians 5:8-11

There is nothing good and righteous about witches, demons, ghosts, etc. Hold those symbols in God’s light. What do you see? This view of our world through “God-goggles” is the standard that we, as Christians, are called to adhere to.

“You cannot drink the cup of the Lord and the cup of demons too; you cannot have a part in both the Lord's table and the table of demons.”
1 Corinthians 10:21

I praise God for pumpkin pie, falling leaves, hay rides, chilly air, and anything else He has given us with the glorious autumn season. However, I believe God’s made one thing perfectly clear to me...Halloween was never part of that gift.

“But if serving the LORD seems undesirable to you, then choose for yourselves this day whom you will serve… But as for me and my household, we will serve the LORD."
Joshua 24:15

As Christians, let's find something better to do on that day, like, look at the stars and enjoy God's goodness.  Plus there's some neat things happening that night in the sky.