Here is an excerpt from an article about Halloween. It is a great article and it would be worth your time to read the entire article at Challies Dot Com.
(To be fair, I made a comment about a section of the quote here on 10.26.2006).
The truth is that I have several convictions regarding Halloween. I despise the pagan aspects of it. I am convicted that my children should not dress as little devils or ghosts or monsters. But I am also convicted that there could be no worse witness to the neighbours than having a dark house, especially in a neighbourhood like ours which is small and where every person and every home is highly-visible. We know that, if we choose not to participate, the neighbors will notice and will smile knowingly, supposing that we feel too good to participate. We have nothing to fear from our neighbours or from their children. So my children will dress up (my son as a police officer and my daughter as a princess) and we will visit each of our neighbours, knocking on their doors and accepting their fistfuls of candy. Either my wife or I will remain at home, greeting people at our door with a smile and a handful of something tasty. If the kids are deemed too old to trick-or-treat, they'll be forced to sing a song to merit any handouts. Our door will be open and the light will be on. And we trust that the Light will shine brightly.
My encouragement to you today is to think and pray about this issue. I do not see Halloween as a great evangelistic occasion. I do not foresee it as a time when the people coming to your door are likely to be saved. But I do think it is a time that you can prove to your neighbors that you care about them, that you care about their children, and that you are glad to be in this world and this culture, even if you are not of this world or this culture. Halloween may serve as a bridge to the hearts of those who live around you who so desperately need a Savior.