1030 All who die in God's grace and friendship, but still imperfectly purified, are indeed assured of their eternal salvation; but after death they undergo purification, so as to achieve the holiness necessary to enter the joy of heaven.
1031 The Church gives the name Purgatory to this final purification of the elect, which is entirely different from the punishment of the damned. The Church formulated her doctrine of faith on Purgatory especially at the Councils of Florence and Trent. The tradition of the Church, by reference to certain texts of Scripture, speaks of a cleansing fire:
As for certain lesser faults, we must believe that, before the Final Judgment, there is a purifying fire. He who is truth says that whoever utters blasphemy against the Holy Spirit will be pardoned neither in this age nor in the age to come. From this sentence we understand that certain offenses can be forgiven in this age, but certain others in the age to come.
1032 This teaching is also based on the practice of prayer for the dead, already mentioned in Sacred Scripture: "Therefore [Judas Maccabeus] made atonement for the dead, that they might be delivered from their sin." From the beginning the Church has honored the memory of the dead and offered prayers in suffrage for them, above all the Eucharistic sacrifice, so that, thus purified, they may attain the beatific vision of God. The Church also commends almsgiving, indulgences, and works of penance undertaken on behalf of the dead:
Let us help and commemorate them. If Job's sons were purified by their father's sacrifice, why would we doubt that our offerings for the dead bring them some consolation? Let us not hesitate to help those who have died and to offer our prayers for them.
Righteousness is imputed (Protestant doctrine), therefore the conclusion does not follow from the premises. A person can enter heaven despite sinning and being attached to sin due to the fact that God's grace "covers" man, hiding his impurity and making him fit to enter heaven. For Scripture says that "God made him who had no sin to be sin for us, so that in him we might become the righteousness of God." (2 Cor 5:21)
Reply: Righteousness is not imputed, but rather infused. [Infused Righteousness] But aside from this, the objection suggests that sin and impurity are allowed to enter heaven under the cover of God's righteousness; it is "smuggled" into heaven, but never destroyed. This seems to contradict Premise 1, which makes clear that no sin or impurity can enter heaven, covered or otherwise. Therefore, even if righteousness is imputed, we must accept that our impurity which is covered will be ultimately cleansed, and so the conclusion still follows.
"Make friends quickly with your accuser, while you are going with him to court, lest your accuser hand you over to the judge, and the judge to the guard, and you be put in prison; truly, I say to you, you will never get out till you have paid the last penny."
Commentary: Jesus says that if you don't make friends with your accuser, you will be punished until you have paid the full price for your error. If you die before you can pay this price, there must be a way to settle this debt, since Jesus says that "you will never get out" until it has been paid. Purgatory is simply the affirmation of this fact.
"According to the commission of God given to me, like a skilled master builder I laid a foundation, and another man is building upon it. Let each man take care how he builds upon it. For no other foundation can any one lay than that which is laid, which is Jesus Christ. Now if any one builds on the foundation with gold, silver, precious stones, wood, hay, stubble— 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."
Commentary: Paul says that when Jesus returns in the Second Coming (on "the Day"), every person's conduct on earth will be judged. Paul uses the analogy of a building which is built on the foundation of Jesus. If one's conduct is good, his building will survive. If one's conduct is poor, his building will be burned up, but the person will survive. Both are saved because both are cases of people who have built their lives upon the foundation of Jesus. However, even salvation does not excuse someone from a final purification prior to entering heaven. Paul is talking about the Second Coming, but the same must hold true for an individual's particular judgement as much as it holds true for the general judgement.
Passages Compiled: Mat 5:25-26, 1 Cor 3:10-15
The Acts of Paul and Thecla
Abercius
The Martyrdom of Perpetua and Felicity
Tertullian
Cyril of Jerusalem
Gregory of Nyssa
John Chrysostom
Augustine
Tradition: The Acts of Paul and Thecla, Abercius, The Martyrdom of Perpetua and Felicity, Tertullian, Cyril of Jerusalem, Gregory of Nyssa, John Chrysostom, Augustine