According to Catholic Church teaching,
our “post-life” condition will continue until the last judgment. The souls of
those who die in the state of grace but are not yet free from all imperfection
will wait to make expiation for unforgiven venial sins or endure temporal
punishment due to venial and mortal sins that have already been forgiven, and
by so doing, will be purified before they enter heaven.
Although the doctrine of purgatory is not explicitly stated in the Bible, belief in its existence is intimately related to the biblical doctrine of divine judgment. In the Old Testament, prayer and sacrifice of expiation for the dead appear only in the Book of Maccabees (2 Mc 12:39-45). According to the text, when Judas Maccabee and his men arranged for the fitting burial of the soldiers of his army who had died it was discovered that they had worn pagan amulets contrary to the prescriptions of the Mosaic law, and Judas concluded that God had punished the soldiers for this sinful practice. God’s just judgment was praised, and prayers were offered on behalf of the victims. A collection of 12,000 drachmas was then gathered and sent to Jerusalem to have expiatory sacrifices offered for those who had fallen in battle.
The inspired author of the second book of Maccabees, a firm believer himself in the resurrection of the dead, argued that if he had not hoped that the slain should rise again, it would have been useless and foolish to pray for them when dead, but to do this with a view towards the splendid reward that awaited those who died in godliness, was a holy and pious thought. Therefore, Judas made atonement for the dead that they might be freed from sin. According to the traditional interpretation of this passage, those who had led good lives were purified by prayer and sacrifice for their sins.
Purgatory is a term used only in western Catholic theology for the place of punishment and purification where the souls of those who have died in a state of grace undergo such punishment as is still due for forgiven sins, and make expiation for their unforgiven venial sins before being admitted to the beatific vision.
In this explicit form, the doctrine is not found before the 12th century, but elements of it are much more ancient, especially the notions that not all souls are condemned to hell or are worthy of heaven at the time of death, and that prayer for the dead is invaluable. The former of these notions developed only gradually, partly because so long as the Church looked for an imminent end of the world, there was little interest in an interim state where souls were asleep or waiting, and partly because of a reluctance to encourage laxity by blurring the clear-cut alternate fates of heaven and hell.
I cannot resist quoting St. Paul: “We want you to be quite certain, brothers, about those who have died, to make sure that you do not grieve about them, like other people who have no hope. We believe that Jesus died and rose again, and that it will be the same for those who have died in Jesus” (1 Thes 4:13).
The eastern Church came to admit of an intermediate state, but refrained from defining it so as not to blur this distinction. It combined with this doctrine a firm belief in the efficacy of praying for the dead, which was a constant feature of both eastern and western liturgies. Such prayer is held to be unintelligible without belief in some interim state in which the dead might benefit.
In the west, there was much more curiosity about the intermediate state. St. Augustine occasionally remarks on a purifying fire after death (De Civitate Dei, 21,26) and on the value of the Church’s prayers for those who die in the communion of the Church.
St. Thomas Aquinas taught that in purgatory any unforgiven guilt (culpa) of venial sins must be expiated and any punishment (poena) for sins, both mortal and venial, still remaining at the moment of death must be given.
Dante Alighieri, in his Divina Commedia, describes powerfully the holiness of God, who required from men and women absolute purification in purgatory before entering the eternal joy of heaven.
Finally, we have Pope Boniface VIII who organized the first Catholic jubilee year in 1300 and granted plenary indulgences to all those who made the pilgrimage to Rome in that Holy Year.
Blessed John Newman depicts purgatory as a peaceful place of final purification, a sort of angelical hospital where souls are gently nursed until they are ready to enter heaven. In Rome, however, there is a Museum of the Holy Souls which presents a rather more terrifying image – a place of torment from which those enduring the cleansing fires long to escape. One thing is for sure – if this is what purgatory is like, one dreads to think what would happen in hell.