Been following this conversation with Bellarmine from a sedevacantist viewpoint for a while and I think it's kind of a distraction, here's the deal:
Originally when the first ambiguous (and therefore erroneous / heretical?) Vatican 2 document came out, it was thought "Paul VI" was a "pope who became heretical". Hence there was discussion about if he was a pope or not. SSPX took the 1) "sedeplenist" view, he was still a pope but these documents are to be rejected, 2) a "sedeprivationist" view was proposed that he was still a "material pope" (kind of a novel proposition) but he "formally" lost the papacy, and the 3) "sedevacantism" was proposed that Paul VI immediately ceased to be pope upon issuing such errors publicly (since a pope cannot teach error or heresy).
My reading of Bellarmine suggests that he offers opinions on what to do with a "heretical pope"... so the issue isn't settled. Ergo I believe God would not allow this to happen with the Church.
A couple other points here that indicate we should have moved past this thought of "what to do with a heretical pope": 1) sedevacantists shifted the argument over time to arguing Montini was a heretic before being elected to become pope, so he never became pope in the first place. This avoids the question of a "heretical pope" as it is simply declaring his papal election invalid. 2) Presuming "Paul VI" (Montini) was a true pope who fell in to heresy, then the next papal claimant's election (John Paul I) would be considered invalid because he would be a heretic seeking office as pope and heretics cannot become pope.
So the arguments focusing on Bellarmine to me seem like a distraction from the argument that such claimants never became pope in the first place, either of 1) Paul VI or 2) John Paul I.
(Among traditionalists, there also seems to be imprecision as to exactly the status of the Vatican 2 documents' alleged errors. This is because the documents are ambiguous, and so there seems to be a lack of people identifying exactly how ambiguity is treated with respect to error. There are degrees of theological error, see "theological censures" Catholic encyclopedia entry [1]. What I did therefore is to try to find some statement that seems ambiguous which was condemned as heretical and logically equivalent to Vatican 2 statements - that seems to exist and hence it seems you could then logically argue such ambiguities in the Vatican 2 documents are "clearly heretical". If that is the case, sedevacantism necessarily logically follows.)
People cannot even imagine how many illusions we are surrounded by. Word tricks, deceptive-misleading ideas, literal lies and the promotion of ignorance and blind faith into whatever system exists.
It's also on the interpersonal level, just as within politics and courts. The very money you we use is the product of illusion. Not because "it's just paper", but because they can print it arbitrarily to enrich themselves, and we are forced to treat money like a reasonable, agreed-upon currency.
Laymen ripping quotes out of context and posting them on the internet with a picture? Yeah I totally miss that ancient Church practice. Bellarmine said other stuff about that question as well, it's simply an undecided question of "what to do with a heretical pope".
The problem is that people on the Internet have zero authority and also [there are other positions as well](https://dominicansavrille.us/on-the-deposition-of-the-pope-part-2-of-2/). Go to Rome, tell the pope he's not pope because of a quote from 400 years ago, see how many people will take you seriously. Now, there can certainly be *doubt* about whether someone like that is pope, yeah. But Sedes just have to absolutize everything and it's so annoying.
The one problem I have with Sedevacantists is that their #1 problem in life is whether the pope is pope or not. They make that into their whole *identity* and spend hundreds, if not thousands of hours researching that one single question and try to "prove" that they are right. Complete waste of time. Meanwhile they commit sometimes extremely uncharitable acts and *that* will damn them (not the sedevacantism).
The question of whether the pope is the pope is, for now, completely secondary. I get that Sedes want a "strong leader pope", but really, just look at the world. How many "Catholics" are actually Catholic and how many just go through the motions? How many people fall into sin because they don't study their catechism to find out what sin actually is? How many people are infected by modernism, feminism and liberalism (Novus Ordo, neo-SSPX, even some sedevacantists are, to some extent). How many practice "natural" family planning and deny God the existence of a ton of white children (even some sede bishops defend NFP because "Pius XII allowed it, therefore it's okay")? So, those are the actual problems, the pope question is more of an academic exercise. It's quite clear that God wants people to stop "just pray and obey".
I know Sedes are good people at heart, but they just want to "solve" the pope problem and convert everyone to Sedevacantism, before even fixing the problems in their own lives and the lives of their friends. And that just makes them so incredibly annoying, they just come off as incredibly self-righteous.
Originally when the first ambiguous (and therefore erroneous / heretical?) Vatican 2 document came out, it was thought "Paul VI" was a "pope who became heretical". Hence there was discussion about if he was a pope or not. SSPX took the 1) "sedeplenist" view, he was still a pope but these documents are to be rejected, 2) a "sedeprivationist" view was proposed that he was still a "material pope" (kind of a novel proposition) but he "formally" lost the papacy, and the 3) "sedevacantism" was proposed that Paul VI immediately ceased to be pope upon issuing such errors publicly (since a pope cannot teach error or heresy).
My reading of Bellarmine suggests that he offers opinions on what to do with a "heretical pope"... so the issue isn't settled. Ergo I believe God would not allow this to happen with the Church.
A couple other points here that indicate we should have moved past this thought of "what to do with a heretical pope": 1) sedevacantists shifted the argument over time to arguing Montini was a heretic before being elected to become pope, so he never became pope in the first place. This avoids the question of a "heretical pope" as it is simply declaring his papal election invalid. 2) Presuming "Paul VI" (Montini) was a true pope who fell in to heresy, then the next papal claimant's election (John Paul I) would be considered invalid because he would be a heretic seeking office as pope and heretics cannot become pope.
So the arguments focusing on Bellarmine to me seem like a distraction from the argument that such claimants never became pope in the first place, either of 1) Paul VI or 2) John Paul I.
(Among traditionalists, there also seems to be imprecision as to exactly the status of the Vatican 2 documents' alleged errors. This is because the documents are ambiguous, and so there seems to be a lack of people identifying exactly how ambiguity is treated with respect to error. There are degrees of theological error, see "theological censures" Catholic encyclopedia entry [1]. What I did therefore is to try to find some statement that seems ambiguous which was condemned as heretical and logically equivalent to Vatican 2 statements - that seems to exist and hence it seems you could then logically argue such ambiguities in the Vatican 2 documents are "clearly heretical". If that is the case, sedevacantism necessarily logically follows.)
1. https://www.newadvent.org/cathen/03532a.htm