Sorry Pax, you say there is no doctrine,

There's not. 

but I quoted what sedes believe is indeed "the doctrine" which was posted by a sede.

This has nothing to do with my original point.  Some sedes will believe in 1 explanation; others won't.  But their conclusion could still be correct. 

+Bellarmine and all the other theologians wouldn't have debated about sedevacantism if it weren't (at least theoretically) possible.  Sedevacantism isn't a heresy.

No, what is Catholic is that which Catholics have believed always and everywhere, which is that there are two ways for a pope to lose his office, death and resignation.

St. Robert had his theological opinions which may or may not be right - which, as you are well aware, would not be the first time one of the great Fathers held a wrong opinion.

I'm pretty sure St. Robert did not consider the disunity among the faithful that is an unavoidable result of his opinion, but because we're living it, we should, and some of us do.

Dear Stubborn,
If it is true that once a man is elected Pope, no matter what he does, he stays in the papal office until his death or abdication; as an enemy of the Church, all I have to do is to put my men on the Throne of Peter.  I do it by using my organization to put them into the seminaries and begin climbing the ladder of the hierarchy.  Eventually, I will have enough of them to elect not only the pope I need, but even more to follow.  Then I put an antichrist to lead all the "catholics" under the banner of the Keys of Peter to their eternal damnation.

Dear Stubborn,
If it is true that once a man is elected Pope, no matter what he does, he stays in the papal office until his death or abdication; as an enemy of the Church, all I have to do is to put my men on the Throne of Peter.  I do it by using my organization to put them into the seminaries and begin climbing the ladder of the hierarchy.  Eventually, I will have enough of them to elect not only the pope I need, but even more to follow.  Then I put an antichrist to lead all the "catholics" under the banner of the Keys of Peter to their eternal damnation.

That is, *IMO* pretty much what happened.

Some odd 40 years ago, we used to listen to cassette recordings of Fr. O'Connor, who pretty much preached what you just said.

In short, their doctrine consists of heretical pope = no pope, 

Even though they could be correct, it's still not a doctrine.  And it's overly-simplistic.

To them it is a vital and most necessary part of the faith.

Right, and this is where the extremism comes into play.

Yep.  And this is exactly what has happened.  And God has allowed it.

Even if every Trad on earth became Sede today...what does that solve?  Nothing.  All Sedeism does is say that the Throne of St Peter is not occupied by a Catholic, but by a usurper.  What then?  Does Sedeism solve the LARGER issue of indefectibility?  No.  How could God allow a usurper to gain the papacy?  Isn't this a theological problem too?  Yes.  Does Sedeism solve this?  No.  Does Sedeism explain how God could allow the V2 church to "eclipse" (to use Our Lady of LaSalette's words) the True Church?  No.

So let's not pretend that the papacy is the ONLY issue/mystery/problem of this present crisis.  It's one of many, many problems. 

Sedeism is an explanation (a partial one at that), not a solution.

Pax. Jesus, St. Paul and St. John warned specifically about "the False Prophet," the "man of sin," the Son of Perdition." Why? Because he, that specific man, is the key sign of the end times. And he, that specific man, is the person who will "deceive even the elect."

Sacred Scripture tells us to focus on this specific man, so that we can avoid his influence and be delivered from his deception which will lead many to Hell.

Pax. Jesus, St. Paul and St. John warned specifically about "the False Prophet," the "man of sin," the Son of Perdition." Why? Because he, that specific man, is the key sign of the end times. And he, that specific man, is the person who will "deceive even the elect."

Sacred Scripture tells us to focus on this specific man, so that we can avoid his influence and be delivered from his deception which will lead many to Hell.

Christ also warned us of (the many) "wolves in sheep's clothing".  These men have to be avoided too.  The point being, we avoid heretics.  All of them.  False Prophet or not.  Sedeism solves nothing.  We have to be wary of heretics in all areas of life.

Hello hgodwinson and welcome to the debate.

The idea of believing in an invalid election, like believing in the pope is not the pope, is only opinion. That's all it is.
Like +ABL saying one day we may say the pope is not the pope - that was his opinion at that time. Like the saints and fathers who taught a heretic pope loses his office, this was their opinion at that time. The whole idea of sedeism is nothing more that opinion that among many, has morphed and been elevated into a de fide doctrine of the Church - without the Church ever having believed or taught it.   

A lot of crazy thinking is corrected by clear challenges, and there have been many, many challenges that have been presented to the sedes for their consideration right here on CI that either go unanswered or are completely ignored, such as the post you replied to - presumably because there is no getting around the truth of it, and in order to wholly accept that truth, the sede belief is threatened. So it is another challenge placed into the ignored-by-sede file, which is a huge file btw.

After posting this, and to show you what I mean in reference to the underlined above, here is a quote by a sede from another sede thread....

I don't mean to sound like a broken record but, many people, myself included do not believe a particular Pope ever lost any office. Just that Roncalli never gained the Office in the first place. So I am seeing a disconnect between your arguments and this specific position I put foreward. Your arguments are against Sedes who believe a particular V2 Pope lost his office, not against the the "invalid election" argument. Perhaps I am missing something. 

Agreed that "sedeism" (as some kind of human ideology) solves nothing. But if someone thinks it's no big deal to God to think the "man of Sin" is the real Pope of HIS HOLY CHURCH, then I think that person is going to experience what St. Paul called "the operation of error." And he are going to bring it down on himself because, through hard-headedness, he refused to listen to the charitable warnings of fellow Catholics:

Bergoglio is the "man of sin." He is the "man, not canonically elected, raised to the Pontificate, who, by his cunning, will endeavor to draw many into error and death," that St. Francis Of Assisi warned about. And those who continue to act as if he is the Vicar of Christ are helping him "draw many into error and death." That is a scandal.

But now you are ignoring the words of Our Lord who said: "Beware of false prophets..."

No one here disputes the pope(s) is a man of sin. But the warning to us from Our Lord is to not listen. His warning does not tell us to insist he is a false pope (prophet). Our Lord's point in warning us is, as Pax said: "The point being, we avoid heretics.  All of them.  False Prophet or not." 

What you are saying is apparently that we cannot avoid heretics when it comes to the pope, unless he is not the pope. This is error.

One thing you have to always keep in the forefront in all of this is that all those who, as you said, "experience what St. Paul called "the operation of error" did/do so of their own free will and against Our Lord's warning - and they will suffer the consequences of not heeding Our Lord's warning.

As a child in the 60s I experienced this exact thing with my own relatives and friends, I witnessed them with my own eyes and ears lose the true faith for the new faith -  because they did not "beware" - that’s why they have what they have, that’s why they’ve chosen it, that’s why they fight for it, and its why they continue to absorb it, they cling to it and they love it, because they did not beware they were willingly deceived.