What if Purgatory were real - let's take the best possible "purgatory" scenario using the "Wonderful Purgatory" model that some here have suggested as our template.
You arrive in purgatory - on your way to heaven - and you find that you no longer have the devil and demons to tempt you to evil. What is more nobody in purgatory tries to tempt you to sin.
Whahoo!!
Better still - you find that you no longer have a sinful nature. No more inner carnal nature driving you toward sinning.
Whahoo!! again!. This must be heaven!.
Well then "oops!" you do have a few rough edges... a bit of a "fixer upper" with that tendency to doubt or gossip. And of course "no sinning in purgatory" -- that is not allowed!. Time to brush up on your "commandment keeping". (wouldn't want to show up in heaven still trying to get to "one day without sinning")
But the good news is that purgatory is designed to get you to "graduate" as the sweetest, kindest - most joyful and unselfish saint -- with nothing but goodwill for all others!! And nobody there is sinning so you are getting lots of help.
You will spend time in peaceful gardens of unimaginable beauty and you will have mentors encouraging you in worship, songs, praise, sharing Bible stories - and the model of kindness and love for others.
Well after a few thousand days of this paradise - someone comes up to you and says "hey you are ready for heaven" but you respond --- "I have become so unselfish and so loving of others here - I would like to stay for another 10 days or so just to make sure that I have no chance at all of marring the perfection of heaven with even the remotest possibility of a defective character on my part".... and your wish is granted in this scenario.
You decide that as a post-grad you would like a "ministry for others" and you decide to go to the gates and "welcome the newcomers" helping others get oriented just as others helped you when you first entered.
A man pops into view at the gate - and it is clear from the not-so-peaceful look on his face that he has "a few issues". some "whopping defects of character" to be worked out.
Well this is what Purgatory is for!! You welcome him with open arms and offer to be his guide and help him find the perfect spot for peaceful relaxation and meditation. This is going to be a blessing for both of you.
But just as you start into your welcome and intro --- he suddenly has a puzzled look on his face - gets a bit dizzy and then POOF!! he is gone!.
What happened! you ask. One of the other post-grads informs you that this is what happens to people when someone on earth earns a plenary indulgence for them -- an indulgence that actually gets the "funds transfer as promised" --
"Yeah but that guy had a few unresolved issues - some real rough edges" you are worried.
"Too bad -- guess the people in heaven will be in for a bit of a shocker" - comes the much anticipated response.
OR does that other post-grad say --
"There is an instant-fixer zapper that we have where all of this Purgatory time is not needed they zap you into heaven and all your character defects are instantly gone - they never really needed this purgatory step at all - it was just a form of entertainment to make life more interesting and to create a need for indulgences for those who do not like the idea of this sort of paradise, and besides in the early days it was a good source of revenue to flow into the church from both rich and poor concerned about stories they were being told regarding departed loved ones".
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At which point our story ends -- and we begin to see how it is that all of this man-made not-in-the-Bible not-the-gospel fictional story might fly in the dark ages - but not in the light of day -- and not at all with the "punish" and "Same as the fires of hell" verbiage so often associated with "Purgatory".
To be fair it has three purposes.
1. initially to make revenue off of the fear generated from stories told the living about the departed.
2. To emphasize the discretion and good-graces of the RCC in rescuing/saving the already-saved "if the RCC so wishes".
3. To provide a "wide road" to heaven - where all but the worst "get heaven" no matter their unchristian character defects at the end of their life.
There are some major heresies alive and well in church today regarding after life, one would be Purgeotory, another that we simply cease to exist, and other is Universalism!