如何用英文说明万圣节的历史

All Saints’ Day
All Saints’ Day, also Allhallows or Hallowmas, festival celebrated on November 1 in the Roman Catholic and Anglican churches, and by the Orthodox churches on the first Sunday after Pentecost, in honor of God and all his saints, known and unknown. It became established as a church festival early in the 7th century when the Pantheon in Rome was consecrated as the Church of the Blessed Virgin and All Martyrs. Pope Gregory IV gave the custom official authorization in 835. November 1 may have been chosen because it was the day of one of the four great festivals of the pagan nations of the north, and it was church policy to supplant pagan with Christian observances.
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