So, is it to be ignored? Why is it in the scripture? It is one thing to say, with Agrarian: "This is how the fathers understood it: the condemnation in Matthew 18:34 describes the eternal and not temporal punishment". It is another to simply dismiss it because it is a parable.
Let us summarize: You dismiss the gospel because it is in parables. You dismiss the book of Macabees because Luther did not like it (that is the same Macabees that is described in 2 Timothy as "inspired of God, is profitable to teach, to reprove, to correct, to instruct in justice, that the man of God may be perfect, furnished to every good work", which you need to keep in mind next time you justify the superstition of Sola Scriptura with this verse). You dismiss the 2000 years of practice of praying for the dead because Luther invented a new religion. Why is your opinion of any consequence?
you admit that it is an invention of your denomination
The Catholic Church is not a denomination, the Purgatory is not an invention, and I admitted nothing of the kind. It is a doctrinal development like any other my Church has been asked by Christ to do (Luke 22:31-32; John 21:15-17).
"It is a doctrinal development like any other my Church has been asked by Christ to do (Luke 22:31-32; John 21:15-17)."
Well it might interest you to know the Holy Spirit disclosed to our church, with proper scriptural citations and no need for doctrinal development, that when a believer dies he/she goes directly to be with the Lord and does not go to any intermediate state or rely on others to call to God's attention (in case He forgot) the good works of the deceased or any penance or prayers on the part of the living on the deceased's behalf.
Maybe your church's doctrinal development on this point has not matured yet. The old "milk and meat" analogy of Hebrews.