All Souls’ Day is a church holiday designed to commemorate loved ones who have died. The different branches of the church have different histories with All Souls’ Day.
Roman Catholicism: The official name of All Souls’ Day in the Roman Catholic Church is “The Commemoration of All the Faithful Departed.” Originally, this feast day was celebrated around Easter time, but was eventually moved to November 2, the day after All Saints’ Day (unless the 2nd falls on a Sunday, in which case All Souls’ Day is moved to the 3rd). Roman Catholics pray, celebrate Mass, visit cemeteries, and give alms in memory of those believers who they believe are held in purgatory, in hopes that their souls will be released to heaven. The rest of November is also spent praying for the dead.
Eastern Orthodoxy: Tradition says that in 893 Byzantine Emperor Leo VI wished to dedicate a church to his wife. He was denied, so he dedicated it to “all souls,” ensuring she would be remembered in the celebrations. A feast once devoted only to martyrs was altered to include all the faithful. The Orthodox Church celebrates All Souls’ Day several times throughout the year, including four times during or around Lent.
Protestantism: The observance or non-observance of All Souls’ Day is varied throughout Protestantism. Some Protestant denominations merged All Souls’ Day with All Saints’ Day. Others have abolished All Souls’ Day entirely. Others observe it entirely in a secular sense by tidying up the gravestones of departed loved ones.
Although related to pagan festivals of the dead, All Souls’ Day is much younger—from the Middle Ages, at the latest. It is not biblical. Although it is fine to groom cemeteries and remember our departed loved ones, purgatory does not exist, and there is no reason we should pray for the dead.