An opportunity to dress up, especially as creatures of darkness, before we celebrate the lives of those who have led us to the light, is a good way to relieve existential and spiritual tension. Mardi Gras celebrations in New Orleans function in much the same way. There is neither harm nor foul in masking our identities, having a bit of harmless fun, and reveling, in some small way, in the darker side of our natures. Indeed, by doing so with the conscious intention of limiting this darkness to an alternative identity for a specific purpose, we force a control over that darker side of ourselves that might otherwise control us. It might even be said to be a kind of playful discipline, or perhaps disciplined form of play, in order to prepare ourselves for the somber yet happy thought that our lives have been influenced by those who have gone before us.
To those Christians who find something evil or horrible about Halloween, all I can say is, get over it. Dress up, relax, and remember that the night (Eve) is not stronger than the light (the Feast of All Saints).
UPDATE: Courtesy of Tintin at Sadly,No! comes this example, proving me right.
The word "holiday" means "holy day." But there is nothing holy about Halloween. The root word of Halloween is "hallow," which means "holy, consecrated and set apart for service." If this holiday is hallowed, whose service is it set apart for? The answer to that question is very easy-Lucifer's!
The best line in this article comes immediately following this quote, in which she calls Lucifer part of "the demonic godhead". And to think I pay $35 a month for this kind of rich, sugary goodness . . .