A Christian who was arguing against Halloween would probably lean on a case like this: Halloween (we assume) has its origins in pagan festivals that celebrated either the dead (Parentalia) or the spirit-world (Samhain), and most of its trappings, such as costumes, trick-or-treating, and jack-o-lanterns, might possibly have to do with these non-Christian elements. Christians should "avoid all appearance of evil," and certainly ought not to be honoring pagan (possibly demonic) spirit-beings, so it's best just to abstain from all Halloween activities. Further, some other religions and a few anti-Christian cults have adopted Halloween as one of their high holy days, and we don't want to be seen supporting the Satanists, Wiccans, and Neo-Pagans in their respective delusions.
On the other hand, a Christian arguing for the celebration of the holiday might rely on a case like this: Halloween (as near as we can tell) actually has its origins in ancient Christian practice. The name itself derives from "All Hallows Eve," that is, the night before one of the great feasts of the church calendar, All Saints Day on Nov. 1. Most of its trappings, such as costumes, trick-or-treating, and jack-o-lanterns, probably have to do with medieval Christian beliefs about the journey of the soul after death, not with pagan rituals. As it's currently celebrated, Halloween is mostly harmless fun and a good opportunity to connect with our communities; conversely, abstaining from Halloween makes us look rather unneighborly, gives our churches an impression of nitpicky legalism to outsiders, and cuts us off from interacting with our communities on one of the few civic occasions nowadays where neighbors actually cross paths. And, while we certainly don't want to be seen as walking arm-in-arm with the practices of Satanists, Wiccans, and Neo-Pagans, neither should we abandon the field and let them claim a charming civic holiday for their own ends.
Of the two perspectives, I favor the latter. I prefer to err on the side of loving my neighbors, and if that means shoving copious handfuls of chocolate into the waiting arms of faux zombies and witches, then so be it. Those of you who regularly read my posts know that I'm a history buff, so the historical argument is the most interesting part of this to me. Unfortunately, on this question, it's a bit of a wash. There's probably no way to settle the matter with certainty. A lot of historians have made intriguing connections between Halloween and pagan festivals, and a lot of historians have made just as compelling a case for a merely Christian development of the holiday. Our sources in late antiquity and the early medieval period simply do not speak with much clarity about such details in the lives of ordinary people. If I were to make a guess, however, based on my academic training in anthropology and history, I would lean toward the interpretation that Halloween is almost entirely based on medieval Christian culture, not on any pagan predecessors.
|The Pantheon in Rome, a former pagan temple converted into a church|
|The Apostle Paul writing his letters|
The debate about Christians practicing Halloween, it seems to me, falls along the same lines. If your conscience compels you to abstain from all Halloween activities, then abstain. But if you want to use the holiday to connect with your neighbors and celebrate a long Christian tradition, then go right ahead.
(Images - Top inset left: Samhain ritual at a boulder in Sweden, 11/7/2009, photo by Gunnar Creutz, public domain; Middle inset right: "Icon of All Saints," by Simeon Khromoy, c.1600; Middle inset left: "Roma, Pantheon," 1/10/2013, photo by Lalupa, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license; Bottom inset right: "Saint Paul Writing His Epistles," attributed to Valentin de Boulogne, c.1619, oil on canvas)