It's a relatively new phenomenon. Comparison with memories of a childhood spent in the midst of mainstream Protestant congregations in Minnesota may be somewhat less than valid:

Even more insidious and more frightening in the long run is that some Christian groups have decided that Halloween is an evil thing. October now brings media stories on how elementary schools around the country have replaced traditional Halloween costuming and parades with more mundane "Fall Festivals." Parents are quoted as saying, "celebrating Halloween is the same as celebrating Satan's birthday."

I was raised in Oklahoma in the Southern Baptist denomination. My Christian upbringing was about as fundamental as it gets. Yet at no time was Halloween ever preached or propagandized against when I was a child. My mother, as devout a Baptist as one can find, delighted in making me extravagant costumes (and delights to this day in seeing her grandchildren costumed and enjoying Halloween.) It seems that only in the last decade or so have Christians decided that the holiday is sinful and satanic and should not be celebrated.

Perhaps this negativism is merely a reaction against what is otherwise an almost too intense social acceptance of the holiday. Perhaps the truth was only lately revealed unto the faithful.

Source [emphasisi added; original dated 1997]

Here is a clearer example of what Mary Anne and her colleagues -- that is to say, educators of children in publically-funded institutions -- have been confronted with in recent years:

If it's October, it must be Halloween. Kids are already clamoring for costumes (we'll see a lot of Harry Potters), and stores are gearing up for the annual economic bonanza.

But for many school administrators, Halloween is no longer any fun. They're caught in the crossfire between parents who support and parents who oppose Halloween observances in the classroom.

What to do? Eliminating Halloween because of religious objections from some parents angers many others who insist on keeping it as a "fun time for kids." But ignoring complaints will only further alienate people who already see public schools as hostile to their faith.

The solution might be simpler if Halloween were a First Amendment issue. However, the courts are unlikely to rule that classroom celebrations are an unconstitutional promotion of religion by school officials.

Yes, it's true that Halloween has religious roots in Samhaim, an ancient Celtic festival. It's also true that some contemporary religious groups have adopted Halloween as their religious holiday. But in our popular culture, Halloween has long been severed from any religious meaning or intent — particularly in the schools. Thus, despite the fact that some Christian and Muslim parents see Halloween as filled with (negative) religious images and messages, judges will likely view public-school celebrations of Halloween as having a secular purpose that neither advances nor endorses religion.

Here's an analytical overview of the evangelical stance, from <a href="http://www.religioustolerance.org/hallo_ev.htm>ReligiousTolerance.org

And now, for a few examples of virulent anti-Halloween-ism... Did you know that trick-or-treating was Satan worship?

From: "Resurrection Resources Staff"
Subject: Help others say "No" to Halloween

Dear Home School Family,

Every year we are all confronted with the dilemma of Halloween. What
does it mean? How do we handle it? How do we share with others our
beliefs about its non-scriptural basis?

Here at Resurrection Resources we are always trying to help our families communicate effectively with others by preparing educational materials and books that teach, aid, or enhance communication skills. That is why we prepared a fictional novel about saying "No" to Halloween. 'Joy' is easy-to-read and a delightful story that always blesses anyone who has tried to communicate their beliefs to another.

[ . . .]
You can find out more about our 'Joy' book at
http://www.thefathersbooks.com/fiction.htm

Source -- and here's a quote from that "Resurrection Resources" page about the book:

So, for the price of a couple of bags of candy, you can be spreading the real truth about the satanic roots of Halloween as well as drawing neighbors to the Messiah!

The October 31st holiday that we today know as Halloween has strong roots in paganism and is closely connected with worship of the Enemy of this world, Satan. It is a holiday that generally glorifies the dark things of this world, rather than the light of Jesus Christ, The Truth.

Source.

And here's the worst I could stand to read -- not only foaming at the mouth, but historically ignorant, from Garner Ted Armstrong (any surprise?):

Why do many Baptists, Methodists, or Episcopalians celebrate purely Catholic customs, which antedate Christianity itself by thousands of years? To most, it simply does not make any difference. Millions see no harm in cavorting about dressed like a demon, or a mummy, or a skeleton; see no harm in celebrating so-called "Christian" holidays with all the accoutrements of paganism. One might as well ask why people keep Christmas, with its symbols of tree worship, eggs and orbs, the holly wreath and mistletoe. Actually the Word of God condemns both.

Hallowe'en has its origins in purely pagan mythology. No wonder it is the most important day to Satanists and those dabbling in the occult. First, it is based entirely on the notion that Satan, or "Samhain," as the pagan Druids called him, who was "Lord of the dead," and who had consigned the "departed souls" of the loved ones of the celebrants to inhabit, say, the body of a mouse or a rat during the past year, could be induced into giving the soul of the loved one a "lighter sentence" in the ensuing year, say, in the body of a cat!

Since the Druids taught that the night of the eve of Pomona, or Hallowe'en, was the one night of the year when spooks, goblins, demons, ghosts, ogres, poltergeists, witches and the like were most likely out and about, they sought to spook them away by lighting "bonfires" (the "bon" in "bonfire" just as in "hot cross bun" comes from bous originally; Horus, or Nimrod - the sun god), or by carving a leering face in a pumpkin, placing a lighted candle inside, and placing it in a window. Offerings of food were left outside, hoping to placate wandering demons.

So, today, "Christian" people allow their children to dress up like any of the hideous caricatures of demons (or perhaps a famous person or Hollywood star), and act out the parts of the demons by chirping "trick or treat" to residents in their homes. The vernacular is "Pony up, or I wreck the joint!" Thus, children are taught extortion and blackmail at a very early age; the childish "protection" racket is alive and well.

By the way, the remainder of that "sermon" reveals as much anti-Catholic bigotry as it does anything else.

To be fair, the anti-Halloween movement is not entirely confined to rabid fundamentalist Christians. There is also a vocal, though tiny, minority in American Jewry which insists it should not be celebrated because it is a Christian holiday! Here's an example.