It was believed and taught by Druids that on October 31st, Samhain called together all the wicked souls that had died within the past twelve months. These departed souls would have been condemned to inhabit the bodies of animals (hence the origin of animal sacrifice to free them). These souls of the dead demanded to be appeased by the living through food, shelter, and sacrifice. If adequate food, shelter, and sacrifice were not provided, these evil spirits would cast spells, cause havoc and terror, and haunt and torment the living. If a sacrifice was not willingly provided, the home was cursed by placing a six-pointed star in a circle upon the door. An evil spirit would use this as a point of entrance to take the victim's life. This drawing of the hexagram is where we get our phrase "putting a hex on someone."

Druids believed human sacrifice offered the ultimate appeasement of Samhain. After the human sacrifice, a giant pumpkin was hallowed out, Samhain's smiling face carved into it, and a candle of human tallow (Body fat) was placed inside. - Gene Aven "Halloween" 

The "Jack-O-Lantern" was the ancient symbol of a damned soul. The name was derived from a man named Jack, who was believed to be wandering to find a place of rest. He is wandering in darkness with his lantern until Judgement Day. Since there was much superstition, the people would carve out pumpkins or turnips and place candles in them to ward off the evil spirits.  

** So, whether we look at the historical origin of Halloween or the way it is celebrated today in our culture, there is still a clear connection to death, fear, and darkness.