Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you...
2 Corinthians 6:17
"Halloween's origin can be found in the ancient Celtic festival of 
Samhain (pronounced saw-en, meaning 'end of summer'). For the Celts who celebrated their new year on November 1st, the day marked the end of the harvest and the beginning of winter, the end of light and the beginning of darkness, the end of life and the beginning of death.
By A.D. 43 the Romans had successfully conquered most of the Celtic lands.
---During the next 400 years, Samhain was merged with two Roman holidays:
Feralia, a day when Romans commemorated their dead, typically at the end of October, and secondly Pomona, a day of honoring the Roman goddess of fruit and trees.
In 609 A.D. Pope Bonafice IV established the Catholic feast of All 
Martyrs' Day in honor of the early Roman martyrs, and this feast was later expanded by Pope Gregory III to include all saints and is still practiced today on November 1st as All Saints' Day (known also as Hallowtide or All Hallows).
November 2nd is also celebrated as All Souls' Day mainly to honor the saints and pray for the lives of the recently departed who have not reached heaven yet.
Some of the Halloween traditions can be seen in the festival surrounding All Saints' Day.
There were traditions of
---ringing bells for the souls in purgatory; poor people, mostly children, would go from house to house "souling"—they would get 'soul cakes' in exchange for prayers for departed loved ones;
---people even wore costumes in order to protect themselves from wandering souls of the dead."
Minno