Popping some popcorn.
The myth of purgatory is rejected because of what the Bible actually says, like the event of the Rapture, no purgatory during the twinkling of an eye. we are transformed to ‘fit for eternal living, physically, in soul, and to match our new born status with the Righteousness of Christ. But it appears pope Gregory was not familiar with the letters to the Thessalonians ...
God is not going to ‘cleanse’ the flesh, He has told us through Paul that He, GOD, will give us a new soul and body when Jesus comes in the air to gather us and take us to The Father’s House.