Halloween is a celebration that has roots 2000 years old and is based on the Celtic festival of Samhain pronounces sah-win. This festival occurred each year at the end of harvest on October 31 when it was time to take stock of supplies and slaughter livestock for the coming winter. It was one of the major festivals of the Celtic year. Bon fires were lit in honor of the dead and to keep them away from the living. The bon fires served the dual utilitarian purpose of being a place to burn the remains of the animals slaughtered for the coming winter. The Celts believed the veil between the living and the dead became thin at this time and the dead could bring illness or poor crops if not distracted. Dressing in costumes and masks to mimic the dead was believed to distract them from causing harm and prevent them for recognizing the person wearing the costume.
The holiday was thought to be brought to America by Scottish and Irish immigrants. In these countries the carved pumpkin was actually a carved turnip or rutabaga! It was only in America where Pumpkins were plentiful, and it was realized, much easier to carve than a turnip that pumpkins began to be used as Jack-o-Lanterns.
The tradition of the Jack-o-Lantern is based on the Irish myth of Stingy Jack. As the story is told, Stingy Jack tricked the devil and in retribution the devil condemned him to wander the earth in darkness. Stingy Jack carved out a turnip to hold an ember to light his way. Ever since that day, according to the myth, he has roamed the earth trapped between heaven and hell. The tradition of carving pumpkins and placing candles inside was thought to keep evil spirits and Stingy Jack away.
The name Halloween is a shortened version of All Hallows Even, another name for All Saints Day. In the Christian tradition All Saints Day is a day to honor the dead that have gone to heaven. Parts of the Christian liturgy even mentions praying for help from the departed saints. The name Halloween actually comes from these Christian traditions.
In the Celtic tradition the festival that later was called Halloween was mysterious but not considered in any way evil. The festival was meant to challenge the ascendancy of the darkness while acknowledging and respecting its mystery, to celebrate good harvest and psychologically prepare for the coming winter. The Celts believed their departed dead did not really die but went to another place different from the living world but still in contact with it especially on this festival when the veil between the two worlds was felt to be thin. Their druid or priest would use this time to attempt to find guidance for the coming year from the departed ancestors.
People across cultures have different myths and stories to account for death, the passing of the seasons and many other archetypal events. The consistency of these myths across cultures seems to point, not to any inherent evil, but to a deep human need to make sense of these events in our lives.