Halloween once had a beloved place in the pantheon of American holidays, as wholesome as Thanksgiving turkey or Fourth of July fireworks. But some concerned Christians are peeking under Halloween's mask and seeing Satan -- and persuading a number of schools, churches and homes around the country to alter drastically or shut down altogether their traditional celebrations.

Schools in Howard County have notified parents this year not to send their children to class dressed as ghosts or witches, and black cat decorations are disappearing from classrooms. Elementary schools in Ohio and New York are replacing the traditional Halloween parties and parades with a "Harvest Festival" celebration or "Read Across America Week."

Churches in Atlanta and Sacramento, Calif., that once created elaborate haunted houses as fund-raisers are instead holding "Hallelujah Night," where the child with the best Biblical costume wins the biggest prize.

All of which suggests that in the 1990s, even Halloween has become a battleground in the conflict over family values.

"We hear so much about the supposed separation of church and state and how Christianity has no place in the schools," said a recent newsletter of Citizens for Excellence in Education, a conservative organization based in Costa Mesa, Calif. "Yet the schools promote the Halloween celebration which is so obviously tied to the religion of witchcraft. We must ask why."

This approach is "very clever," said Deanna Duby, education policy director of People for the American Way, a civil liberties group that monitors the religious right. "If you can define something as a religion, then you have a constitutional argument for getting it out of the schools."

But she added, "I think it's very important for school districts to allow kids to opt out" of Halloween celebrations because "there are parents out there who are genuinely concerned."

Halloween originated as the ancient Celtic harvest festival of Samhain (pronounced Sow-en) in Ireland and ancient Britain, when the spirits of the dead were thought to revisit their homes, and all manner of ghosts, goblins, witches and demons were believed to be roaming about. In the 9th century, the Catholic church grafted the Christian onto the pagan when it named Nov. 1 All Saints' Day, and Oct. 31 became All Hallow's Eve.

The tradition was introduced to the United States in the last century by Irish immigrants as a largely secular occasion for trick-or-treating and making mischief. But some conservative Christian activists are now unearthing its pagan roots in their attack on the tradition.

"The devil is real. It's not something that is just fun and games," said Allan Siegel, media relations director for Jeremiah Films, a Christian film and video company in Hemet, Calif. "There are satanic organizations, demonic organizations... . This is their holiday, and that's why we don't want to glorify it and teach our kids about it."

Jeremiah Films has sold, at $19.95 apiece, nearly 30,000 copies of a videotape called "Halloween: Trick or Treat," a professionally produced documentary that conjures up the tradition's sinister side. There is footage of modern-day druids and witches dancing around bonfires and raising chalices in smoky rooms. A woman identified as "Sarah, Witch Queen of Germany," recalls a ritual where a woman passed out when a horrible voice spoke through her.

Most haunting of all, the video features an interview with a bearded young man who claims he was sexually and emotionally abused as a child captive of a satanic cult. One Halloween, he says, he was forced to plunge a knife into the heart of his friend, a little girl named "Becky," as she hung bound on an altar.

"There are children all over the world who are losing their lives on Halloween night," said the man, identified in the film as Glenn Hobbs, a former Satanist. "Nobody wants to face the facts of what's going on."

What may sound preposterous to some has found an audience in Bible study sessions and house meetings around the country. The Halloween video is distributed by the same company that has sold more than 100,000 copies of a videotape accusing President Clinton of murder and money laundering, a video that the Rev. Jerry Falwell has been criticized for promoting.

Becky Varian of East Liverpool, Ohio, said she was stunned to learn the true history of Halloween at a Bible study meeting. "As a kid it was one of my favorite holidays," said Varian, 35, who teaches a course on death and dying at a business college.

Varian told her child's teacher that she didn't want her 7-year-old son Dylan participating in Halloween activities. She dissuaded Dylan from dressing as the demonic Jason from the movie "Friday the 13th," explaining that "the Bible has scripture that would consider that evil." As a concession, Dylan will dress up this year as a hunter, like his Dad -- "something not so scary."

"As a Christian I believe you can open these spiritual doors, like playing with a Ouija board," Varian said. As a youth, she said, she was curious about the supernatural and in college was involved in a group that channeled spirits. "I wouldn't want my kids doing that. Some might think it's fun and games, but we believe as Christians that's opening the door to Satan."

Opponents cite press reports to support the case against Halloween. Almost every Halloween, stories surface of satanic ritual activity backed up by evidence of gory animal remains. Psychopathic murderers, like the notorious Night Stalker or Charles Manson, say Satan made them do it. Teenage music idols tuck into their lyrics homages to the devil.

And there is a little-known but burgeoning neo-pagan movement in this country and in Europe, part of the explosion of interest in New Age religion. Consisting mostly of white, educated professionals, they gather on Halloween and solstices in forests and fields for newly invented rituals that mix ancient Celtic customs with nature worship. These groups are not Satanists and they do not practice sacrifice, said Isaac Bonewits, 45, archdruid of a 300-member fellowship that supports a "1-800-DRUIDRY" hot-line. But he is accustomed to accusations of devil worship from conservative Christians.

"Anything that teaches children that religion and spirituality are under their control, something they can be creative with, is going to be threatening to particularly conservative branches of monotheism," Bonewits said.

Attempts to exorcise Satan from public schools have become more common as conservative Christians become better organized in parents' groups and win seats on school boards. They have fought to remove books that they believe have occult and satanic themes from school libraries and class reading lists. Among those challenged last year were "Scary Stories to Tell in the Dark" by Alvin Schwartz, "Dracula" by Bram Stoker, "The High King" by Lloyd Alexander and "Halloween ABC" by Eve Merriam.

On a unanimous vote, the PTA board at Columbus Intermediate School in Bedford, Ohio, canceled this year's Halloween party, sending parents a note saying there were "questions and concerns" about the occasion because of "personal, moral and religious beliefs." In Schaumburg, Ill., five of 28 schools this year are replacing costume parades with events like quiz games because of concerns that the traditional celebrations glorify the occult, violence and gangs.

Many school districts, like Howard County, Md., have asked children "not to wear costumes that would offend anyone, like witches or devils, or anything related to the occult or satanic," said Patti Caplan, spokeswoman for the Howard County school district. "It's a matter of trying to live in a more diverse society, and that's what we're trying to teach our children to do."

The concerns about the satanic roots of Halloween come in an era of growing alarm about violent movies and television, and violent crime. Even parents who aren't spooked by the occult are nudging their children away from the goriest Freddy Krueger, Jason and demon masks.

At Toys R Us last week, witch costumes were still among the top five best-selling costumes. But ranking ninth was a generic angel costume with wings and a halo, more popular than even Batman.