I don’t think so, I think it makes perfect sense, what does not make sense to me is what most Protestants are taught that the Catholic Church teaches. Purgatory is 100% Biblical, as will be shown below.
I depends on what you mean by “already forgiven”. If you mean that by “Accepting Jesus” you are forgiven of all your sins, including those you have not yet committed, I would disagree. If you mean that the forgiveness of our sins is through God’s grace, and that grace is brought through the Passion, Death and Rising from the Dead of Jesus, I agree. If you mean that any sins you commit after you are incorporated into Christ, are forgiven by God’s grace when you are sorry for your sins, and make an amendment to try to not sin again, yes I agree with that.
As to Purgatory, it does not in any way deny the effecasy of Christ’s Sacrifice, but rather it supports it. All Catholics believe that the forgiveness of sins was made real by the Sacrifice of Christ. But there is forgiveness of guilt, and there is the penalty that is due for our sins. If the penalty had been lifted, and all sins even future sins have been forgiven then we would never get sick, or die. Sickness and death is we are told by the Scriptures the wages of sin.
Having been forgiven, we are still responsible to repay the penalty. If we steal from someone, or give false witness, then we must make restitution for what we have done. As for the offence against God, we still have that penalty to pay. We see in the story of Ananias and Saphorah, that when they lied to the Apostles, God considered it a lie to God, and they died there on the spot.
When we die, we undergo what is called the particular, or individual, judgment. Scripture says that “it is appointed for men to die once, and after that comes judgment” (Heb. 9:27). We are judged instantly and receive our reward, for good or ill. We know at once what our final destiny will be. At the end of time, when Jesus returns, there will come the general judgment to which the Bible refers, for example, in Matthew 25:31-32: “When the Son of man comes in his glory, and all the angels with him, then he will sit on his glorious throne. Before him will be gathered all the nations, and he will separate them one from another as a shepherd separates the sheep from the goats.” In this general judgment all our sins will be publicly revealed (Luke 12:2‚Äì5).
Some charge, “The word purgatory is nowhere found in Scripture.” This is true, and yet it does not disprove the existence of purgatory or the fact that belief in it has always been part of Church teaching. The words Trinity and Incarnation aren’t in Scripture either, yet those doctrines are clearly taught in it. Likewise, Scripture teaches that purgatory exists, even if it doesn’t use that word and even if 1 Peter 3:19 refers to a place other than purgatory.
Christ refers to the sinner who “will not be forgiven, either in this age or in the age to come” (Matt. 12:32), suggesting that one can be freed after death of the consequences of one’s sins. Similarly, Paul tells us that, when we are judged, each man’s work will be tried. And what happens if a righteous man’s work fails the test? “He will suffer loss, though he himself will be saved, but only as through fire” (1 Cor 3:15). Now this loss, this penalty, can’t refer to consignment to hell, since no one is saved there; and heaven can’t be meant, since there is no suffering (“fire”) there. The Catholic doctrine of purgatory alone explains this passage.
Purgatory makes sense because there is a requirement that a soul not just be declared to be clean, but actually be clean, before a man may enter into eternal life. After all, if a guilty soul is merely “covered,” if its sinful state still exists but is officially ignored, then it is still a guilty soul. It is still unclean.
Catholic theology takes seriously the notion that “nothing unclean shall enter heaven.” From this it is inferred that a less than cleansed soul, even if “covered,” remains a dirty soul and isn’t fit for heaven. It needs to be cleansed or “purged” of its remaining imperfections. The cleansing occurs in purgatory. Indeed, the necessity of the purging is taught in other passages of Scripture, such as 2 Thessalonians 2:13, which declares that God chose us “to be saved through sanctification by the Spirit.” Sanctification is thus not an option, something that may or may not happen before one gets into heaven. It is an absolute requirement, as Hebrews 12:14 states that we must strive “for the holiness without which no one will see the Lord.”