All Souls began with the emphasis on remembering those who had died, broader than just the martyrs. In addition it was cast wide into Catholic theology. In that tradition , the church commemorated all of those who have died and now are in Purgatory, being cleansed of their venial (forgiven) sins and the temporal punishments for the mortal sins that they had confessed and atoning before entering fully into Heaven.
All Souls (Nov. 2) and Halloween (Oct. 31)
Halloween originated in Celtic cultures and spread to Christian.
The word Halloween is a contracted form for All Hallows’ (holy persons or saints) Evening- the day before All Saints.
Halloween has been on Oct 31 because of the Celtic traditions. Halloween also not only focused on death but on the concept of death blending in the supernatural. The Church scheduled All Saints and All Souls after Halloween. The emphasis on All Soul’s focused on those who had died only and did not dwell on stories surrounding death.