Yet again Another commonly misunderstood teaching of the Church concerns the topic you keep bringing up time and time again Aineo is Purgatory. Purgatory is not a second-chance for damned souls to repent. Instead it is a state of cleansing and purification for souls destined for heaven. Also Purgatory is not a means to earn our way to heaven, but a gift from God preparing us to see Him face to face. Even though not explicitly referred to by name, the Bible does allude to it, especially in terms of purging fire.
The word Purgatory is related to the verb - to purge - which means to cleanse or purify. According to the Catechism of the Catholic Church (CCC)
Only saved souls - those dying in God's friendship - can go through Purgatory onto heaven. To better understand Purgatory in the light of Christ's sacrifice of redemption, we need to first focus on the consequences of sin.
Through Baptism and faith (Mark 16:16), we become friends of God and receive sanctifying grace - the privilege of eternal life. This is all made possible by Christ's redemption of us. Unfortunately very serious sin - mortal sin - "kills" our friendship with God. By willfully committing mortal sin, we reject God, and we lose this sanctifying grace (Titus 1:16). Christ's sacrifice on the Cross can still redeem our friendship with God; however, we must repent and seek God's forgiveness through the Sacrament of Reconciliation (Confession). If we do not repent and die in this graceless state, then we suffer the loss of eternal life. This loss is eternal punishment or hell (Matt 25:46). Hell is not punishment from a vengeful God, but the natural consequence of rejecting God - the Source of joy and life. Our redemption does not interfere with our free will; we can still reject our Lord through serious sin (Heb 10:26-27).
Now not all sin is mortal (1 John 5:17). Some sin is not serious enough to kill our friendship with God, but still it is harmful to us and neighbors. The mess (e.g. scandal) caused by our sin needs correction. This correction is temporal punishment (Hebrews 12:5-11). We can be corrected and cleansed through personal penance on earth or later in Purgatory - thanks to our Redeemer, Jesus Christ.
Jesus in the Gospel talks about this correction and indirectly Purgatory at the end of His parable on forgiveness:
And in anger his lord delivered him to the jailers (torturers), till he should pay all his debt. So also my heavenly Father will do to every one of you, if you do not forgive your brother from your heart. [Matt 18:34-35]
In this passage there is no mention of God punishing very serious sinners but only those who sin by not forgiving others. Also the punishment referred to here is not eternal as in hell (Mark 9:47-48) but only temporary - "till he should pay all his debt."
Purgatory is a temporary state for souls in friendship with God (i.e. saved) who need cleansing from the bad effects, mess, scandal and attachments (attraction to sin) still remaining from forgiven mortal sins and less serious venial sins. Such tainted souls, though saved, cannot enter heaven directly. As stated in the Bible: "But nothing unclean shall enter it (heaven)..." [Rev 21:27]. These souls need to be purged of all "uncleanness", no matter how slight before seeing God face to face (Rev 22:3-5). Eventually all souls in Purgatory will go to heaven.
St. Paul makes allusions to this in terms of fire in his Epistle to the Corinthians:
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. [1 Cor 3:12-15]
Our works built on Christ will be tested. Inferior works - "wood, hay and stubble" - will be purged by "fire", while only the "gold, silver and precious stones" will survive for heaven. The clause, "he will suffer loss," implies temporary hardship and punishment, even though he will be saved. St. Peter in his Epistle also reminds us that the genuineness of our faith "is tested by fire." [1 Peter 1:7]
Now some Christians object to the doctrine of Purgatory and cite the repentant thief in the Gospel:
And he said, "Jesus, remember me when you come in your kingly power." And Jesus said to him, "Truly, I say to you today you will be with me in Paradise." [Luke 23:42-43]
According to them, since Jesus promised this particular repentant sinner to be in "Paradise" with Him that very day, there is in general no need for Purgatory. This argument has several flaws though. First Christ could have granted this particular repentant sinner what the Church refers to as a "Plenary indulgence" - the total remission of temporal punishment due to already forgiven sins. Secondly Christ could have known that the thief's suffering on his cross was sufficient personal penance to purify his soul. However a more interesting point is that Jesus after His death did not go immediately to heaven. According to the Epistle of St. Peter:
For Christ also died for sins... being put to death in the flesh but made alive in the spirit; in which he went and preached to the spirits in prison, who formerly did not obey... [1 Peter 3:18-20]
Immediately after His death, Jesus "went and preached to the spirits in prison." Now this "prison" is surely not heaven, nor can it be hell since the souls in hell could not benefit from Christ's preaching. It is a third state. Perhaps the repentant thief joined Christ there that very day. In comparison to hell, Purgatory could rightly be described as Paradise.
Peace