I have read the Catholic Answers document explaining the roots of purgatory with interest and here is my conclusion.
All Christians agree that we won’t be sinning in heaven. Sin and final glorification are utterly incompatible. Therefore, between the sinfulness of this life and the glories of heaven, we must be made pure. Between death and glory there is a purification.
What part of the doctrine of substitution atonement don’t you understand?
We have been purified.
Ephesians 5:25-28
25Husbands, love your wives, just as Christ loved the church and gave himself up for her 26to make her holy, cleansing her by the washing with water through the word, 27and to present her to himself as a radiant church, without stain or wrinkle or any other blemish, but holy and blameless. 28In this same way, husbands ought to love their wives as their own bodies. He who loves his wife loves himself.
Colossians 1:21-23
21Once you were alienated from God and were enemies in your minds because of] your evil behaviour. 22But now he has reconciled you by Christ’s physical body through death to present you holy in his sight, without blemish and free from accusation— 23if you continue in your faith, established and firm, not moved from the hope held out in the gospel. This is the gospel that you heard and that has been proclaimed to every creature under heaven, and of which I, Paul, have become a servant.
Thus, the Catechism of the Catholic Church states: “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. The Church gives the name purgatory to this final purification of the elect, which is entirely different from the punishment of the damned” (CCC 1030–1).
Either we have been purified perfectly or we haven’t been purified at all. Ephesians 5:25-28 and Colossians 1:21-23 are for everybody not a select bunch.
The concept of an after-death purification from sin and the consequences of sin is also stated in the New Testament in passages such as 1 Corinthians 3:11–15 and Matthew 5:25–26, 12:31–32.
Ok let’s have a look at these scriptures.
Firstly 1 Corinthians 3:11–15
For it to make sense wit’s better to read the whole chapter but so this isn’t to long I’ll start at verse 6.
6I planted the seed, Apollos watered it, but God made it grow. 7So neither he who plants nor he who waters is anything, but only God, who makes things grow. 8The man who plants and the man who waters have one purpose, and each will be rewarded according to his own labour.
We are talking about labouring for the kingdom here.
9For we are God’s fellow workers; you are God’s field, God’s building.
10By the grace God has given me, I laid a foundation as an expert builder, and someone else is building on it. But each one should be careful how he builds. 11For no one can lay any foundation other than the one already laid, which is Jesus Christ. 12If any man builds on this foundation using gold, silver, costly stones, wood, hay or straw, 13his work will be shown for what it is, because the Day will bring it to light. It will be revealed with fire, and the fire will test the quality of each man’s work.
So as we grow in Christ false doctrine is burnt away. That which is not of Christ is burnt away as we journey with him. This is Theosis.
14If what he has built survives, he will receive his reward. 15If it is burned up, he will suffer loss; he himself will be saved, but only as one escaping through the flames.
This is because what Christ did is enough and he will survive by having the false doctrines and foundations burnt away.
This has nothing to do with purgatory at all.
Next Scripture Matthew 5:25-26
25"Settle matters quickly with your adversary who is taking you to court. Do it while you are still with him on the way, or he may hand you over to the judge, and the judge may hand you over to the officer, and you may be thrown into prison. 26I tell you the truth, you will not get out until you have paid the last penny.
To say that the prison here is Purgatory is stretching it a bit. In short, what Jesus is saying is blessed are you when you are merciful for then you will be shown mercy.
Next scripture
Matthew 12:30-32
30"He who is not with me is against me, and he who does not gather with me scatters. 31And so I tell you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven. 32Anyone who speaks a word against the Son of Man will be forgiven, but anyone who speaks against the Holy Spirit will not be forgiven, either in this age or in the age to come.
The way purgatory is gleaned out of this verse is rather dogmatic. Some how because there is an age to come there has to be a place of cleansing called purgatory. Of course this is nonsense. The phrase ‘in this age or the age to come’ is an expression of finality.