What is Halloween? Is it worshipping demons? Is it the night when spirits walk the earth?
The word "Halloween" is derived from several things: All Saints' Day (November 1), Eve of All Hallows (All Hallows Eve), or Hallow Even.
The celebration of Halloween was originally the New Year's Eve of the Celts, the eve of Samhain or "Winter's Eve." It was believed that the dead, or the disembodied spirits of all who had died throughout the preceding year, would come back in search of living bodies to possess for the next year. According to lore, it was their only hope for the afterlife.
Those who didn't want to be possessed by these lost souls would extinguish the fires in their homes to make them cold and inhospitable, dress up in ghoulish costumes, and parade around their villages making as much noise as possible to frighten away the spirits looking for a live body to possess. This ceremony took place on the night of October 31. Food and drink (which you might say accounted for the crazy actions of the villages and not the fear of being possessed) would be left out for these costume wielding villagers. It wasn't until the 1840s that the custom of Halloween was brought to America by Irish immigrants fleeing their home country's potato famine.
The evil side of Halloween was an idea propagated mainly by the Church, which maintained that the gods and goddesses and other spiritual beings of traditional religions were diabolical deceptions and manifestations of the Devil. Therefore, the customs associated with Halloween were always represented as "evil": ghosts, human skeletons, symbols of the dead, Satan, witches, and other such devilish beings.
A Brief History of Halloween

Trick or Treat
In ninth-century Europe, it was believed that after you died, your soul remained in limbo. To send souls up to Heaven, Christians used to go "souling." On October 31, All Souls' Day, they would go around to all the villages and collect "soul cakes"—cakes made out of square pieces of bread with currants. The relatives of the dead passed the cakes on to the Christians, who in return promised to pray for the souls of the deceased relatives so that they would go to Heaven. The more cakes given, the more prayers were said.
This custom is thought to have been where the practice of trick-or-treating originated, but it's not the only one. It's also been said that trick-or-treating came from Britain, where it was know as "Mischief Night" and was particularly popular in parts of northern England.
It may also have come from an old Irish peasant practice where people would go from door to door to collect money, breadcake, cheese, eggs, butter, nuts, apples, and more in preparation for the festival of St. Columbkill.
Jack-o-Lanterns
The Jack-o'-lantern came from Irish Folklore. As the tale goes, a man named Jack (a local drunkard known for his quick temper) got extremely inebriated at the local pub on All Hallows' Eve. As Jack's life began to slip away, the Devil appeared to claim his soul.
Jack, wanting desperately to stay alive, begged the Devil to let him have just one more drink before he died. The Devil agreed. Jack was short of money, so he asked the Devil if he would assume the shape of a sixpence so that Jack could buy a final drink. Afterwards, Jack suggested, the Devil could change back to himself and claim Jack's soul.
Improbably, the Devil agreed—but once he had assumed the shape of the coin, Jack seized it and shoved it into his wallet, which was miraculously fortified by a cross-shaped clip.
The Devil, now stuck in Jack's wallet, went crazy—yelling and screaming and ordering Jack to release him at once! Displaying questionable decision making, Jack made yet another deal with the Devil, promising to release him if he agreed not to bother Jack for an entire year. The Devil was so anxious to be released that he agreed.
Jack was so ecstatic to have escaped the Devil and be given a new lease on life that he mended his ways...for a little while, anyway. In the beginning, Jack was good to his wife and children and began attending church and giving to charity. But slowly and surely, Jack slipped back to his old ways.
On the following All Hallows' Eve, the Devil appeared to Jack once more and demanded that Jack accompany him to his death. Believing he could once again outsmart the Devil, Jack somehow managed to con him into getting an apple out of a nearby apple tree. Jack even went so far as to hoist the Devil up the apple tree.
Once the Devil was up the tree, Jack took out a knife and carved a cross into the trunk of the tree, trapping the Devil. For the second time in as many years, the Devil yelled and screamed and demanded to be set free. He even went so far as to promise Jack that if he let him go, he'd grant Jack another ten years of peace.
Perhaps having learned his lesson, Jack decided that wasn't good enough and demanded that he never be bothered by the Devil again. The Devil agreed and was released from his apple tree trap.
Almost immediately, Jack went back to his drunken and angry ways. Before a full year had even passed, his body gave out and he died. When Jack tried to enter Heaven, he was refused entry because of his evil ways. Not wanting to exist in limbo forever, Jack even tried to enter Hell—but even the Devil refused him entry, apparently having not forgiven Jack for the tricks he played on him.
Finally, the Devil had mercy. He threw Jack a hot coal to help him find his way through the darkness of limbo. Jack put the piece of coal into a turnip, and it became known as a Jack-o'-lantern. It is said that on All Hallows' Eve, if you look hard enough, you can still see Jack's flame burning dimly as he searches the darkness for an eternal home.
The use of Jack-o'-lanterns as festival lights for Halloween is a custom that descended form the Irish, who used carved out turnips or beets as lanterns. On Halloween, these lights represented the souls of the dead. When the Irish immigrated to America, they discovered pumpkins were far easier to come by than turnips. The Jack-o'-lantern then became a hollowed-out pumpkin lit with a candle.