“Trick or treat!”

That phrase is heard many times throughout the United States in observation of Halloween as children of all ages dress in costumes, parade through neighborhoods and beg for candy.

Excluding the recent commercialization of Halloween, the traditions and customs of the ancient holiday remain similar to its origins, though slightly assimilated into today’s culture.

Scholars trace the roots of Halloween back about 2,000 years to the Celtic holiday of Samhain, said Nikki Bado-Fralick, assistant professor of philosophy and religious studies.

Celebrated in Ireland, Samhain, or summer’s end, was a time when people reflected on the past year, celebrated the end of the harvest season and prepared for winter. Celts viewed Oct. 31, the day before their new year began, as a time when the boundary between the worlds of the living and the dead was blurred.

“[Halloween is when] the door between the world of the living and the world of the dead is open,” Bado-Fralick said. “Insights and ideas pass through a lot easier.”

Celtic priests built large, sacred bonfires where people gathered to burn crops, animals and possibly even humans, as sacrifices to the Celtic gods. During the celebration, Celts wore costumes and attempted to tell each other’s fortunes.

On the Pagan calendar, Samhain is the final harvest and is often viewed as the beginning of the new year by many Pagan groups. Pagans see this holiday as a time to honor the dead and their ancestors, and share the harvest with those less fortunate than themselves, Bado-Fralick said. They also look back to see what they have accomplished in the past year and look ahead to plan their goals for the next year.

By the seventh century, Christianity had spread into Celtic lands and the Catholic Church attempted to replace the Celtic festival of the dead with a church-sanctioned holiday.

At this time, Pope Boniface IV named Nov. 1 as All Saints’ Day to honor saints and martyrs. The day before Nov. 1 was then called All Hallows Eve, the holiday now known as Halloween.

Halloween did not become popular in North America until the nineteenth century when an influx of Irish immigrants came to America. Before then, Puritans in New England detested the holiday, according to “Halloween: From Pagan Ritual to Party Night,” by Nicholas Rogers.

Bado-Fralick said today’s version of Halloween is a reinterpretation of earlier customs having to do with the harvest.

Many churches today designate days near Halloween to honor people who died in the previous year. Some churches also have fall harvest festivals.

The Catholic Church celebrates All Saints’ Day Nov. 1 and All Souls’ Day Nov. 2.

Catholics believe in the Communion of Saints, which means people who have died and were faithful to Catholicism can be examples and inspirations to others, said Crystal Caruana Sullivan, campus minister at St. Thomas Aquinas Church and Catholic Student Center, 2210 Lincoln Way.

“The church has named a particular group of saints, [or] people who are exemplified for their Christian life, and we look to them as people who made the journey before us and [who can] provide an example for us,” Sullivan said. “We celebrate the whole Communion of Saints — people that have been named particulars as well as people who have not been named officially as saints — as our ancestors in faith.”

All Souls’ Day is a day to remember and honor those who may not yet share in heaven, Donaghy said.

Methodists, Presbyterians and Lutherans also celebrate All Saints’ Day Nov. 1.

“It’s kind of a celebration of those persons who have been really important in our individual faith journeys and [the congregation’s] faith journeys,” said Jim Shirbroun, campus minister at the Collegiate United Methodist Church, 2622 Lincoln Way.

He said every congregation may do something different, but at the Collegiate United Methodist Church, church members name the person they want to honor and light a candle to celebrate his or her life and the impact he or she had on the congregation.

Martie Larson is the campus minister at Collegiate Presbyterian Church, 159 N. Sheldon Ave.

Presbyterians celebrate All Saints’ Day on the Sunday closest to it, Larson said.

“It’s centered around the Communion of Saints being all those that have gone before us in the faith,” Larson said. “We will honor some of those people who have set examples for us in the faith, not just within the denomination, but in our personal lives as well.”

Mark Heilman, associate pastor at Memorial Lutheran Church, 2228 W. Lincoln Way, said Lutherans celebrate both All Saints’ Day and the Protestant Reformation.

The beginning of the reformation is celebrated Oct. 31 because that is when Martin Luther posted a notice outside of a church door to start the reformation, Heilman said.

Cornerstone Church, 56829 U.S. Highway 30, does not participate in All Saints’ Day celebrations.

“We don’t see that same identification that the Catholic Church has with celebrating saints,” said Paul Sabino, director of The Salt Company, a religious student organization affiliated with Cornerstone Church.