From the very beginning, Christians prayed for their dead, especially on the anniversary of the person’s death. But, because of various superstitious practices in the pagan world, it took until the Middle Ages for a special mass and special prayers to be institutionalized. It started with the monks praying for their dead in every monastery connected to Cluny in France.
This feast is based on the frailty of the human condition, that is, that most of us are not quite ready for heaven, to see God “face to face.” So, we need a purgation to be truly worthy of being with God on heaven. This is the basis for the theology of “purgatory.” Let’s remember all the dead today, especially our own dead as we are reminded that “it is a holy and wholesome thought to pray for the dead.”