“FYI. It was not until the Protestant Reformation in the sixteenth century that anyone denied the doctrine of the final purification.”
Please...
Show that a single Apostle believed or taught this.
Show that ANYONE before 100ad believed this
It cannot be done.
Of course, there isn’t a heck of a lot of anything before 100AD, including a lot of the NT!
I hopes this helps to understand the teachings of the Catholic church.
Look at 1 Corinthians 3:14–15: “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.” You see, the Latinate word purgatory means a purgation or burning by fire. Paul in these verses refers to a purgation process whereby a man is saved even though his works are burned away. This is precisely what the Catholic Church teaches. A person at death who still has personal faults is prevented from entering into heaven because he is not completely purified. He must go through a period of purgation in order to be made clean, for nothing unclean will enter heaven (cf. Rev. 21:27).
Furthermore, the New Testament shows a continuity with this idea. For example, Matthew 12:32 says that some people who sin “will not be forgiven, either in this age or in the age to come.” This suggests that there are some sins that will be forgiven in the age to come. If there is no purification after death, then this passage doesn’t make much sense.
On the contrary, the idea of purgatory, when properly understood, is entirely consistent with the love of God. God wants us to be perfect (cf. Matt. 5:48). If we are not perfected by the time we die, we will be perfected in purgatory. He loves us too much to allow us to be less than what he created us to be. Purgatory is not about an angry God inflicting punishment upon his creatures. It is about a loving Father who “disciplines us for our good, that we may share his holiness” (Heb. 12:10).
If we sin deliberately after receiving knowledge of the truth, there no longer remains sacrifice for sins 27but a fearful prospect of judgment and a flaming fire that is going to consume the adversaries.t 28Anyone who rejects the law of Moses* is put to death without pity on the testimony of two or three witnesses.u 29Do you not think that a much worse punishment is due the one who has contempt for the Son of God, considers unclean the covenant-blood by which he was consecrated, and insults the spirit of grace? Hebrews 10:26
So be perfect,* just as your heavenly Father is perfect.d (Matthew 5:48 )
https://www.catholic.com/magazine/print-edition/is-purgatory-found-in-the-bible