According to the Encyclopedia Britannica, Halloween originated with the pagan Celtic festival of Samhain, a day on which the devil was invoked for the various divinations. ‘The souls of the dead were supposed to revisit their homes on this day’, Britannica says, ‘and the autumnal festival acquired sinister significance, with ghosts, witches, hobgoblins .. and demons of all kinds said to be roaming about.’
It is noted by Professor John Hennig, in his classical article on this topic, there is a clear historical relationship between the Celtic concepts of resurrection, Roman Catholic responses to it, and the modern American holiday of Halloween.