Suppose a friend or co-worker comes to you and says:
"The Catholic Church has this massive doctrine of purgatory, invented in the middle ages. The Church used to even sell indulgences to shorten your time in purgatory by a fixed number of days. This doctrine is based on books that don't belong in the Bible. There is no place or region in the afterlife for the saved except heaven. There is no pain in the afterlife, and the minute we die we go to heaven, as Paul says, 'To be absent from the body is to be present with Christ,' praying for people in purgatory makes no sense. Worst of all, it infringes on the sufficiency of Christ's work. It is completely unbiblical. No Protestant could believe it."
What should you say?
Well, the first thing you should say is, "Whoa! Slow down! One argument at a time, okay?" Then go over his arguments with him individually . . .
1. "The Catholic Church has this massive doctrine of purgatory."
This is quite false. As an illustration of this, the section on purgatory in the Catechism of the Catholic Church is only three paragraphs long (CCC 1030-1032). In essence, there are only three points on the matter which the Catholic Church insists: (1) that there is a purification after death, (2) that this purification involves some kind of pain or discomfort, and (3) that God assists those in this purification in response to the actions of the living. Among the things the Church does not insist on are the ideas that purgatory is a place or that it takes time, as we shall see below.
2. "Invented in the middle ages."
The idea that purgatory is a late invention is similarly false. In fact, it has been part of the true religion since before the time of Christ. It is witnessed to not only in such as 2 Maccabees, which itself witnesses to the belief (see below), but in other pre-Christian Jewish books as well, such as The Life of Adam and Eve, which speaks of Adam being freed from purgatory on the Last Day.
It was also part of the true religion in Jesus' day, as the writings of the New Testament show. And it has been part of the true religion ever since Christ's day, as the writings of the Church Fathers show (see the Catholic Answers pamphlet: "The Fathers Know Best: Purgatory" ).
Not only Catholics believe in this final purification, but the Eastern Orthodox do as well (though they often do not use the term "purgatory" for it), as do Orthodox Jews. In fact, to this day, when a Jewish person's loved one dies, he prays a prayer known as the Mourner's Qaddish for eleven months after the death for the loved one's purification.
Because the doctrine of purgatory was held by pre-Christian Jews, post-Christian Jews, Catholics, and Eastern Orthodox, nobody thought of denying it until the Protestant Reformation, and thus only Protestants deny it today.
3. "The Church used to even sell indulgences to shorten your time in purgatory by a fixed number of days."
Concerning this argument, first point out that it really deals with the issue of indulgences, which is a separate matter (see my piece, "A Primer on Indulgences" ). If one wishes to really hear what Catholics have to say for themselves, one subject must be dealt with at a time, not several at once in some kind of "buckshot" approach to apologetics.
Second, indulgences were never sold. At one time, for a period of perhaps two hundred years, it was possible to give a charitable donation to some cause, such as an orphanage or church building fund, as one of the ways in which an indulgence could be obtained. This was no different than Protestant ministries offering something in exchange for a charitable contribution or "love offering" to a worthy cause. However, because of the scandal that Protestants produced, over four hundred years ago (shortly after the Council of Trent) the Church forbade charitable giving as a way of obtaining indulgences.
Third, Protestants are often confused by the number of "days" that used to be attached to indulgences. They have nothing to do with time in purgatory. Indulgences originally arose as a way of shortening a penitential period on earth. The number of "days" that were attached to indulgences were not understood as shortening time in purgatory, but as easing the purification after death by an amount analogous to the shortening of an earthly penitential period by the number of days indicated.
Fourth, because some people were confused by thinking purgatory was shortened by a set number of days with an indulgence, the Church abolished the "day" figures attached to indulgences specifically to eliminate this confusion.
Fifth, the reason that the "days" were never understood to be days of literal time off in purgatory is that the medieval theologians, such as St. Thomas Aquinas, those living at precisely the period when they "days" were attached to indulgences, were very clear about the fact that time does not work the same way in the afterlife as it does here. In fact, they had a special term for it, and would contrast three different temporal modalities -- the ordinary flow of events we experience here on earth, called "time;" the perpetual present that God experiences, called "eternity;" and the middle, less well understood state experienced by those in the afterlife, known as "aeviternity."
So the Church has never said that purgatory involves the same kind of time as we experience here on earth, or even time at all. Thus Cardinal Joseph Ratzinger, no theological liberal, writes that purgatory may involve "existential" rather than "temporal" duration (cf. Ratzinger's book Eschatology). It may be someone one experiences, but experiences in a moment, rather than something one endures over time.
4. "This doctrine is based on books that don't belong in the Bible."
When a Protestant says this, he has in mind 2 Maccabees 12, in which Judah Maccabee and his men pray for their fallen comrades who had "fallen asleep in righteousness" so that they may be "freed from their sins" in the afterlife, and it was a "holy and pious thought" for them to do this.
Thus 2 Maccabees endorses praying for the dead that they may be loosed from the consequences of their sins (for it must be the consequences of sin that are in mind since the saved are not sinning in the afterlife). Since it is not pleasant to be bound to the consequences of one's sins, we can infer some kind of pain or discomfort, and thus the full doctrine of purgatory -- a purification (freeing) after death, which involves some kind of pain or discomfort, and which can be assisted by the prayers of the living.
However, while 2 Maccabees 12 certainly teaches the doctrine of purgatory, the doctrine is in no way "based on" that passage. The doctrine can also be supported from numerous passages in the New Testament, but more fundamentally (and this is what you should point out to the Protestant), it can be derived from the principles of Protestant theology alone.
You see, Protestant are very firm (in fact, insistent) about the fact that we continue sinning until the end of this life because of our corrupt nature. However, they are equally firm (if you press them) about the fact that we will not be sinning in heaven because we will no longer have a corrupt nature. Thus between death and glory there must be a sanctification -- a purification -- of our natures.
This purification may take no time, but as we have seen, this is no barrier to the doctrine of purgatory. The fact remains that between death and glory must come purification, and that is purgatory by definition -- the final purification or, to put it in more Protestant terms, "the final sanctification" or "the last rush of sanctification."