More than 2,000 years ago, the European Christian Church designated November 1 as "the day of the saints of the world".?
"Hallow" means saints. Legend has it that Celts living in Ireland, Scotland and other places moved the festival forward for a day, October 31, 500 B.C.
They think it's the official end of summer, the beginning of the New Year and the beginning of the harsh winter.?
At that time, people believed that the dead soul of the deceased would return to their former residence on this day to find life on the living people, so as to regenerate, and this is the only hope that people can get regeneration after death.
The living are afraid of the soul of the dead to take life, so people put out the fire and candlelight on this day, so that the soul of the dead can not find a living person, and dress themselves as ghosts to frighten away the soul of the dead.?
Afterwards, they will rekindle the sparks and candles and start a new year's life.
兩千多年前，歐洲的基督教會把11月1日定為“天下聖徒之日”。“Hallow”即聖徒之意。傳說自公元前五百年，居住在愛爾蘭、蘇格蘭等地的凱爾特人（Celts）把這節日往前移了壹天，即10月31日。
他們認為該日是夏天正式結束的日子，也就是新年伊始，嚴酷的冬天開始的壹天。那時人們相信，故人的亡魂會在這壹天回到故居地在活人身上找尋生靈，借此再生，而且這是人在死後能獲得再生的唯壹希望。
而活人則懼怕死人的魂靈來奪生，於是人們就在這壹天熄掉爐火、燭光，讓死人的魂靈無法找到活人，又把自己打扮成妖魔鬼怪把死人的魂靈嚇走。之後，他們又會把火種、燭光重新燃起，開始新的壹年的生活。
擴展資料：
節日風俗：
萬聖節前夜是壹年中最“鬧鬼”的時候，各種妖魔鬼怪、海盜、外星來客和巫婆們紛紛出動。在基督紀元以前，凱爾特人在夏末舉行儀式感激上蒼和太陽的恩惠。當時的占蔔者點燃並施巫術以驅趕據說在四周遊蕩的妖魔鬼怪。
後來羅馬人用果仁和蘋果來慶祝的豐收節與凱爾特人的10月31日融合了。在中世紀，人們穿上動物造型的服飾、戴上可怕的面具是想在萬聖節前夜驅趕黑夜中的鬼怪。盡管後來基督教代替了凱爾特和羅馬的宗教活動，早期的習俗還是保留下來了。
孩子們帶著開玩笑的心理穿戴上各種服飾和面具參加萬聖夜舞會，這些舞會四周的墻上往往懸掛著用紙糊的巫婆、黑貓、鬼怪和屍骨，窗前和門口則吊著齜牙咧嘴或是面目可憎的南瓜燈籠。
百度百科-萬聖節