Invincible ignorance is an inculpable lack of a due good -- not a positive quality. It cannot DO anything; a fortiori, one cannot be saved BY it.
As someone wrote,
It is a mistake to say they were saved by their ignorance. Rather they were saved by the truth that God plants on all men's souls and the truth that he gives them the grace to understand. They are simply not culpable for what they are ignornant of.
Romans 2:15:
[13] For it is not the hearers of the law who are righteous before God, but the doers of the law who will be justified.
[14] When Gentiles who have not the law do by nature what the law requires, they are a law to themselves, even though they do not have the law.
[15] They show that what the law requires is written on their hearts, while their conscience also bears witness and their conflicting thoughts accuse or perhaps excuse them
[16] on that day when, according to my gospel, God judges the secrets of men by Christ Jesus.
Pius IX interprets for the deaf: "There are, of course, those who are struggling with invincible ignorance about our most holy religion. Sincerely observing the natural law and its precepts inscribed by God on all hearts and ready to obey God, they live honest lives and are able to attain eternal life by the efficacious virtue of divine light and grace. Because God knows, searches and clearly understands the minds, hearts, thoughts, and nature of all, his supreme kindness and clemency do not permit anyone at all who is not guilty of deliberate sin to suffer eternal punishments."---
QUANTO CONFICIAMUR MOERORE (On Promotion Of False Doctrines, 1863)"Jesus said to them: If you were blind, you should not have sin: but now you say: We see. Your sin remaineth."---Jn 9:41The footnote of the Douay: "
If you were blind "... If you were invincibly ignorant, and had neither read the scriptures, nor seen my miracles, you would not be guilty of the sin of infidelity: but now, as you boast of your knowledge of the scriptures, you are inexcusable."
Watch out then all we who boast of our salvation or "your knowledge" and who work to put up gates where the Church opens them.
The Church and her theologians has clarified the statements of the earlier Popes in this matter. Judge none but ourselves.
There is no twister of doctrine like a Feeneyite twister of doctrine.