SojournerOnEarth:
It won’t happen. Regardless of how much wrong is done, they have taken the position that the Roman Catholic Church cannot fall into heresy. So whatever is taught is true. They cannot admit error, due to a basic statement of ‘I believe the Catholic Church’. Which includes everything that is taught. They simply refuse to look at the evidence to the contrary, and have already determined that it is not compelling, regardless of how compelling it is.
Without the living Magisterium, you can’t in your argument, point to “how much wrong is done”, because Scripture can be interpreted many different ways. The Lutheran and the Baptist can claim the Catholic yardstick is wrong, but if the Lutheran and Baptist yardsticks differ from each other, then the Catholic yardstick is not disproved.
It is hard to come up with “compelling” evidence of error without some objective living standard of truth, against which the Catholic standard be shown to fall short. It does not prove anything to point to popes who were “bad” because infallibility is not the pope’s moral perfection. Infallibility does not mean the pope will always teach the Truth. He might well be silent. Even if a heretic is promoting false doctrine, and even if (in hindsight) it appears the pope should have said something to clarify, infallibility does not mean he necessarily will.
A pope may remain silent for various reasons. He may not know what to say in this situation, he may be afraid of a popular heretic, he may not foresee the long term implications of the heretical teaching. A later council may well (in hindsight) see the damage done by the pope’s silence, and identify a better course action, after the fact, that the prior pope should have followed.
None of this refutes infallibility. If you want to refute infallibility of a pope, you have to “show your cards”. Show us
your yardstick. Justify how
your yardstick is authoritative. Mentioning that a council disagreed with an earlier pope is not evidence, unless you show why
you think that council is authoritative, what they are authoritative on, and what exact doctrine taught directly and dogmatically by an earlier pope, which they claim was erroneous. You have not done any of that.