All Saints’ Day in observed on November 1 by the West (Roman Catholic Church, for instance). In Eastern rite churches, it is observed on the first Sunday after Pentecost. Its purpose is to commemorate the lives of all saints and, based on the belief of the communion of the living and the dead, to ask for their intercession before God.
All Saints’ Day is also called Allhallows. Halloween is celebrated the day before, or, specifically, the evening before All Saints’ Day. The word Halloween is a derivative of Hallows Eve. The emphasis on spirits, goblins, witches, and other dark images came about from the supposition that the dark forces were especially active just before All Saints’ Day in order to hinder the prayer for the dead that would be offered the next day. The practice of trick or treating dates back to the Middle Ages when poor people would go door to door begging food in exchange for their prayers for the dead.
While the Bible teaches that the dead in Christ are alive, it nowhere teaches us to ask for their intercession. Rather, it urges Christians to come boldly before the throne of grace (to God) knowing that we have a great High Priest, Jesus Christ, who ever lives to make intercession for us (Hebrews 4:14–16, 7:24–25). We are to depend upon Christ alone for salvation (Acts 4:12) and upon Him alone for grace for Christian living after salvation. The Bible speaks of Christ as being our one mediator between God and man (1 Timothy 2:5).
 Got Questions Ministries. (2010). Got Questions? Bible Questions Answered. Bellingham, WA: Logos Bible Software.