Purgatory is not so much an intermediary between Heaven and Hell as is often thought, because Heaven and Hell are eternal, while Purgatory is temporal. Purgatory will end at the end of time, and all those in Purgatory will be saved. God may take some out of Purgatory before the end of time, but perhaps not. Regardless, all in Purgatory are saved.
Those who go to Purgatory do not have unrepented mortal sin, but do have unrepented venial sin, or unforgiven temporal punishment due to sin on their soul. A person must be completely purified before he or she can go to Heaven, for otherwise he or she would not be ready to receive the Beatific Vision. While those in Hell have remorse for committing their sins because they are being punished, they have no remorse which arises out of love for God (contrition). However, souls in Purgatory have true contrition, and yet they have to suffer as a means of purifying them.
Purgatory is outside of time and creation, but insofar as we can comprehend, we speak of it in terms of time, because it is temporal. Therefore, the Church has always understood that there exists a way to remit temporal punishment (i.e. time in Purgatory). She does this through indulgences.
When indulgences are brought up in conversation, it usually has to do with cruel clergy demanding money from parishioners and making empty promises that they will go to Heaven. But this conception of indulgences and how the Church administers them misunderstands how an indulgence functions.
The Church still administers indulgences, which are a great blessing God gives to us through the Church. However, if someone is in a State of Mortal Sin, they will go to Hell if they do not repent before they die. No matter how many indulgences they receive, they will not be saved unless their sins are forgiven (something which they can only know for sure is done in the Sacrament of Confession). God can work outside of the sacraments – He is of course not limited by them – but He usually works through them, and Confession is the means He has given mankind, whereby individuals can return to the Lord if they have committed mortal sin. Indulgences do not forgive sins; they reduce the amount of time one has to spend in Purgatory. If we reject the truth of Purgatory, indulgences do not make sense.
The current Church law stipulates that a Catholic can receive a partial or a plenary indulgence. A partial indulgence remits some of the “time” spent in Purgatory, while a plenary indulgence remits all time spent in Purgatory. Before the mid-20th century, Church law stipulated both partial and plenary indulgences, but partial indulgences were specified by periods of time (ex: 500 days indulgence). But the Church, in her prudence, thought that specifying a certain period of time in reference to Purgatory, which is outside of time, was not optimal for helping Christians and non-Christians alike to understand what indulgences are.
One can gain indulgences in a variety of ways. For example, if one prays for the dead at a cemetery in the month of November, they gain a partial indulgence. Praying for the dead is a pious act, and therefore the Church, by her power to bind and loose, can attach indulgences to certain pious acts. However, all of these “indulgences acts” presuppose that one is in a State of Grace, because indulgences have no benefits to those in mortal sin. To gain a plenary indulgence, one must do the indulgenced act (i.e. praying a rosary at a Church, adoring the Blessed Sacrament exposed in a monstrance for at least 30 consecutive minutes, etc.), under the “usual conditions.” The usual conditions are: being in a State of Grace, receiving Holy Communion on the day that the indulgenced act is done, going to Confession eight days before or after that day, and having no attachment to sin. Having no attachment to sin does not mean that one cannot have any venial sin on their soul, but merely that they are not stuck in any habitual sin (i.e. struggling with alcoholism). An indulgence does not take away any venial sin one may have on his soul, for indulgences do not forgive sins. Rather, a plenary indulgence remits all the temporal punishment one has incurred from already-forgiven sins.
There are numerous pieces of evidence for Purgatory and for indulgences in scripture.
In the Maccabean Wars, Judas Maccabeus, a Jewish war hero, and his surviving soldiers “went up to take the bodies of the fallen and to bring them back to lie with their kinsmen in the sepulchres of their fathers” (2 Mac 12:39). But they find under the tunic of every dead man “sacred tokens” worn in adoration of idols (2 Macc 12:40). Judas Maccabeus and the men then “turned to prayer, beseeching that the sin which had been committed might be wholly blotted out” (2 Mac 12:42). If these dead had gone to Heaven, they would not need any prayers, for they would be eternally happy with God. If they were in Hell, neither would any prayers benefit them, for they would inevitably be eternally damned. It only makes sense that they are in need of salvation, yet not beyond it. We call this place when they reside Purgatory, because they are in need of purging of temporal punishment incurred from sin, as well as any venial sin. Therefore, even those who had not yet received the light of Christ understood that some-Purgatory like place existed, even though they would not have used the exact word.
Protestants will often object to the use of this scripture because they do not consider Maccabees to be an inspired book of the bible and because they think the dead committed a mortal sin, and so would go to Hell. For our Protestant friends, we can act for a moment as though Maccabees is not scripture. Still, it provides an accurate historical account of what the Jewish people thought around 150 B.C. This would be the tradition in which Jesus Christ grew up. Thus, many Jews probably believed in some sort of purgatorial place, where the dead who were not in either “everlasting life…[or]…everlasting contempt” would go (Dan 12:2). Christ did not correct this thought, but in fact added to this tradition. He ordered His disciples to “make friends quickly with [their] accuser[s],… lest [they] be put in prison” (Mt 5:25). But this cannot be Hell, for Christ then says that the imprisoned “will never get out till [they] have paid the last penny” (Mt 5:26).
Additionally, one reason the dead soldiers did not necessarily commit mortal sins in wearing the amulets, because although they put their trust in false idols, they could have repented before they died. Only God knows the thoughts of a man’s heart. But, secondly, the Jewish people before Christ did not understand nearly as much about God’s law principally because they had not been given nearly as much grace as those who received Christ’s message were given. Moreover, almost all other religions in ancient Judea were polytheistic, meaning that worshiping the one true God of Israel was all the more difficult than it usually is today. All of these factors do not remove the fallen soldiers’ sin entirely, but they do lessen its gravity. Also, the book indicates that God was pleased with Judas Maccabeus’ prayers for their fallen brethren, for “in doing this he acted very well and honorably, taking account of the resurrection” (2 Mac 12:43). Perhaps the argument could be made that Judas Maccabeus acted honorably by praying for these souls even if they were in Heaven or Hell, because he did not fully understand as much as we Christians now do about death and eternity. But the last two verses of 2 Maccabees 12 indicate that this argument does not hold up. “For if he were not expecting that those who had fallen would rise again, it would have been superfluous and foolish to pray for the dead. But if he was looking to the splendid reward that is laid up for those who fall asleep in godliness, it was a holy and pious thought. Therefore he made atonement for the dead, that they might be delivered from their sin” (2 Mac 12:44-45).
This biblical and purely historical evidence demonstrates the reality of Purgatory. But what about those bishops whose grubby hands stole money from the faithful in exchange for those “get to Heaven free” cards? Well, firstly, Judas Maccabeus “took up a collection, man by man, to the amount of two thousand drachmas of silver, and sent it to Jerusalem to provide for a sin offering” for the dead soldiers (2 Mac 12:43). The text says directly after this verse that this action was “nobl[e] and honorabl[e]” (2 Mac 12:43). But it was also noble and honorable for the donors to donate money for the sin offering. It makes sense, then, that they would receive a reward of the same manner as that which they attempted to obtain from God for others, for “the measure with which you measure will be measured out to you” (Mt 7:2). Thus, they would justly receive a remission of some or all of their temporal punishment due to sin which they had incurred.
Certain priests and bishops did indeed abuse the use of indulgences at certain points in the High Middle Ages, and perhaps did not accurately explain indulgences’ effects. But, as the old phrase goes, abusus non tollit usum – abuse does not take away use. Members of the Church, all of whom are fallible human beings, may have abused the use of indulgences, but the Church never formally taught that the abuse of indulgences was okay, either explicitly or implicitly. Moreover, since Christ has given the Church, through the successors of St. Peter, the power to bind and loose, she has the God-given authority to stipulate what the conditions of receiving an indulgence ought to be, provided those conditions do not contradict God’s law. As evident from scripture, the use of indulgences as a means to shorten or remit the temporal punishment due to sin that one must suffer in Purgatory does not only not contradict God’s Law; it is a charitable and honorable act in the sight of the Lord.
Lest one accuse the Church of relying on too little scriptural evidence for Purgatory and the use of indulgences, we can look to other parts of the bible as well. St. Paul says that “each man’s work will become manifest; for the Day will disclose it, because it will be revealed with fire, and the fire will test what sort of work each one has done. If the work which any man has built on the foundation survives, he will receive a reward. If any man’s work is burned up, he will suffer loss, though he himself will be saved, but only as through fire” (1 Cor 3:13-15).
On “the Day” (the Day of Judgment), some will be saved right away because their works endure through this fire of trial. Some will suffer loss, even though they will be saved, because they will be saved “only as through fire” (1 Cor 3:15). This metaphorical fire must be some sort of purificative suffering which the soul must endure before it attains salvation. It makes sense, then, that a Purgatory exist, wherein a man’s soul will pass through this fire.
A Protestant may object that although this fire will burn a “man’s work,” the man will be separate from his works, and therefore, he will be saved while his work is burned (1 Cor 3:15). But one cannot separate a man from his works. Otherwise, this text would have essentially no significance in detailing our judgment. If a man’s works are burned apart from him, then he is no different from those whose “foundation[s] survive” (1 Cor 3:14). But that would not be just. Likewise, a man’s evil works, his sin, is “engraved…on…[his] heart” (Jer 17:1). The sin becomes part of him. Consequently, if the fire purges his sin, it purges him as well. Moreover, sin itself cannot be purged, in the sense that evil works themselves cannot be made good. Adultery, murder, and theft will never be righteous. But a person can be purged of adultery, murder, and theft. It follows, then, that Purgatory – a place where God purifies one of his sin – exists.