Halloween, or 'All Hallows Eve' is recognised variously in many cultures as a time when the living don masks, and dance around fires and otherwise behave in a way that their Iron Age ancestors would find familiar.
It precedes, by a mere 24 hours, All Saints Day, as though a day of special recognition of Christian saints would be in order, having survived the previous night's debauch and death-dalliance. As its alternative name, The Day of the Dead, suggests, there is an uncomfortable undertow of pagan associations that the Church could never entirely expunge, its solution being to incorporate the pagan traditions into the Christian ceremony.
There's a long history of this in any case. In the second and third centuries after Christ, when the early Church sought to stabilize itself, Greek scholars in Alexandria codified Paul's 'mission statement' by using the structures of rival, arguably more popular religions, namely Hermeticism (cf., Hermes Trismagistus, the syncretic combination of the Greek god Hermes and the Egyptian god, Thoth), and Mithraism.
There are many parallels between Mithraism and Christianity. The former arose 3500 years before Christ, and Christians today would recognise many of its tenets. The epithet, The Unconquered Sun, the lamb carried on the shoulder, the symbolism of the Rock, the Virgin birth at the winter solstice, and so forth, were all associated with Mithra millennia before the Christian period.
It's a popular belief that the reason that masks are incorporated into what in all respects is a pagan ritual, is to ward off evil spirits. This is deemed necessary because at the critical juncture between the Eve and the Day, the membrane separating the world of the dead and that of the living is at its thinnest. One can almost hear the dead whispering to one another, or perhaps to us.
Beyond rooms with HD TVs, designer lamps, and super-fast broadband, something lurks still in our subconscious: the dark, fires and sacrifice, the cold hand upon the shoulder.