Since Halloween itself originated with paganism, it is hardly surprising that its customs are related to pagan belief. According to the Encyclopedia Britannica, In ancient Britain and Ireland, the Celtic Festival of Samhain was observed on October 31 ...

Halloween symbols, customs and practices undoubtedly have had a variety of influences upon them historically. For example, in early American history Halloween was not practiced nor is it primarily an English or Protestant holiday. It was not widely observed until the twentieth century. Initially, it was only practiced in small Irish Catholic settlements until thousands of Irishmen migrated here during the great potato famine and brought their customs with them. To some degree, our modern Halloween is an Irish holiday in origin going back to the Celtic festival. (Ireland is the only place in the world where Halloween is actually a national holiday.) Coincidentally, the rise in popularity of Halloween in America coincides roughly with the national spiritist revival that began in 1848.

The Jack-oâ -lantern. The carved pumpkin may have originated with the witchesâ use of a skull with a candle in it to light the way to coven meetings. But among the Irish, who, as noted, prompted the popularization of Halloween in America, the legend of â Irish Jackâ explains the jack-oâ -lantern. The legend goes: There was a stingy drunk named Jack who tricked the devil into climbing an apple tree for an apple but then cut the sign of a cross into the trunk of the tree preventing the devil from coming down. Jack forced the devil to swear he would never come after Jackâ s soul. The devil reluctantly agreed. Jack eventually died but was turned away at the gates of heaven because of his drunkenness and life of selfish- ness. He was next sent to the devil who also rejected him, keeping his promise. Since Jack had no place to go, he was condemned to wander the earth. As he was leaving hell, the devil threw a live coal at him. He put the coal inside a turnip he had been eating, and has since forever been roaming the earth with his â jack-oâ -lanternâ in search of a place to rest. Eventually, pumpkins replaced turnips since it was much easier to symbolize the devilâ s coal inside a pumpkin.
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Source: www.johnankerberg.org