I tried to do a search here regarding this topic and found it difficult to find exactly what I was looking for.

Wrt the pope issue, I remember reading that what matters is not whether the pope heretic is material or formal, but rather public or private.  I also remember something along the lines that a Catholic can not be a material heretic.  A Catholic can only be a formal heretic.  

Also when St. Robert Bellarmine talks about "heretic pope" what kind of heretic is he talking about?

In this thread, could we elaborate on this including Church teaching, etc that backs it up?

Thanks Mith!  I've got someone on another forum bringing up the formal vs material argument against judging the pope a heretic, so I want to be more knowledgeable.

Material heresy, which is not heresy strictly so called but only error, ("if he is not obstinate, he is no longer in heresy but only in error" - St. Thomas link and "such men are not to be counted heretics" - St. Augustine link )

Thus far we have been discussing Catholic teaching. It may be useful to add a few points about purely theological opinions – opinions with regard to the pope when he is not speaking ex cathedra. All theologians admit that the pope can make a mistake in matters of faith and morals when so speaking: either by proposing a false opinion in a matter not yet defined, or by innocently differing from some doctrine already defined. Theologians disagree, however, over the question of whether the pope can become a formal heretic by stubbornly clinging to an error in a matter already defined.

As is obvious, we are not discussing the possibility of the Pope being in material heresy. No one denies, that mistakenly or by inadvertence, the Supreme Pontiff can fall into material heresy, as a private person.

Only public and formal heretics (this is what St. Robert means by "manifest heretic" for he explains "the manifest heretic is not in any way a member of the Church, that is, neither spiritually nor corporally, which signifies that he is not such by internal union nor by external union") lose the pontificate. The sin of heresy, publicly manifested, is necessary to lose interior supernatural faith, membership in the Church, and the papal power. Someone who is only in error, even grave error, but holds what he does only because he sincerely believes it to the be the teaching of the Church is not a heretic but a Catholic who is gravely mistaken.

Material heresy, which is not heresy strictly so called but only error, ("if he is not obstinate, he is no longer in heresy but only in error" - St. Thomas link and "such men are not to be counted heretics" - St. Augustine link )

Quote from: Van Noort

Thus far we have been discussing Catholic teaching. It may be useful to add a few points about purely theological opinions – opinions with regard to the pope when he is not speaking ex cathedra. All theologians admit that the pope can make a mistake in matters of faith and morals when so speaking: either by proposing a false opinion in a matter not yet defined, or by innocently differing from some doctrine already defined. Theologians disagree, however, over the question of whether the pope can become a formal heretic by stubbornly clinging to an error in a matter already defined.

Quote from: Xavier Da Silveira

As is obvious, we are not discussing the possibility of the Pope being in material heresy. No one denies, that mistakenly or by inadvertence, the Supreme Pontiff can fall into material heresy, as a private person.

Only public and formal heretics (this is what St. Robert means by "manifest heretic" for he explains "the manifest heretic is not in any way a member of the Church, that is, neither spiritually nor corporally, which signifies that he is not such by internal union nor by external union") lose the pontificate. The sin of heresy, publicly manifested, is necessary to lose interior supernatural faith, membership in the Church, and the papal power. Someone who is only in error, even grave error, but holds what he does only because he sincerely believes it to the be the teaching of the Church is not a heretic but a Catholic who is gravely mistaken.

Nishant,

Are you distinguishing between a type of heresy which results in loss of the pontificate and a type of heresy which results in loss of membership?  It's difficult for me to tell.  In either event, public heretics (full stop, without regard to the formal material distinction) are not members.  If you think otherwise, please do quote a source (preferably one from the 20th century, after MCC which helped clarify this issue) which disagrees with that view.

Dear Mith, I cited three Doctors above, and two twentieth century theologians, these latter discussing the specific question of the Pope. Are we agreed at least that the Pope will not cease to be Pope by being merely in material error, but that it is necessary he be a true public and formal heretic?

I could give you other authorities (or more simply, point out that sedevacantist writers today, like Fr. Cekada, as well as Mr. John Lane and Mr. Daly admit that formal heresy is necessary to lose the Papacy) but since you admit that a baptized Catholic can never become a material heretic, then it is seems to me that we largely agree. So, then the only type of public heretic a Pope can become is a public formal heretic, otherwise he is not any type of heretic at all, but only a Catholic in error who is gravely mistaken.

So, the non-sedevacantist view wrt the possibility of a pope being a heretic is that he is merely a "Catholic who is gravely mistaken"?  A pope can be gravely mistaken?  On numerous occasions? How is this possible?

I think if you read this you might have a better grasp on the issue of public heresy and membership: http://www.scribd.com/doc/224429380/Van-Noort-Vol-2-Members-of-the-Church

Trying to print this so I can take it with me outdoors and can't seem to do it.  Boo.

I tried to do a search here regarding this topic and found it difficult to find exactly what I was looking for.

Wrt the pope issue, I remember reading that what matters is not whether the pope heretic is material or formal, but rather public or private.  I also remember something along the lines that a Catholic can not be a material heretic.  A Catholic can only be a formal heretic.  

Also when St. Robert Bellarmine talks about "heretic pope" what kind of heretic is he talking about?

In this thread, could we elaborate on this including Church teaching, etc that backs it up?

A heretic Pope would be a formal heretic.  A purported Pope does not have ignorance as an excuse.  

Check this out:

http://sedevacantist.com/forums/viewtopic.php?f=2&t=1628&sid=6ae4653b13d13e084a443efb7202fc0c

Let's say that someone born and raised in the NO gets "elected" next time, and publicly teaches heresy.  It would be right for the laity to avoid him.  Now a true Pope is not avoided by the laity but embraced and they must, at their eternal peril submit to him.  If this new "pope" continued to maintain V2, the new sacraments, the new canon law, and the new Saints, very public acts "bound on the Church" if he is a valid Pope we could be certain that he was not a valid Pope regardless of whether his heresy is formal or material.  This would be true even if no one warned him he was incorrect, say if the SSPX gave up and stopped communicating with Rome.  

But they will warn him and he will become pertinacious.  

Only a Catholic can be Pope.  So would one  born and raised N.O. who got elected be valid?  Suppose he revoked V2 and all the unCatholic things "bound" on the "Church" since V2?  And never taught heresy publicly even as a private theologian?  Never engaged in heretical acts such as worshiping with false religions?  

It does in essence come down to public/private not formal/material.  We judge in the external.  Formal/material is judged by God.  Public/private pertains to the crime.  Formal/material pertains to the culpability.

It is indeed true that a formal heretic is a Catholic that rejects the faith and that a material heretic is a non-Catholic.  But despite what feeneyites and all that want the gray to be either black or white might claim, there are qualifications.  Many lay Catholics can err in good faith and not be a heretic at all.  A clergyman can slip and teach heresy by mistake and not be a heretic, so long as he admits the error when corrected or repeatedly teach it.  These are all hypotheticals whereas the constant heresies of the V2 "Popes" are realities.  The reality is that a public [nothing about formal or material here] heretic cannot legitimately hold ecclesiastical office.  

The theologians, almost without exception when touching on this issue make no distinction between formal and material from what I have read, merely public and private.  Why would they all leave out such an important distinction?  It is public heresy that destroys the visibility of the Church, not whether one is guilty of it or not.  

Does that help at all?

This is what I believe the Catholic Church has taught.  It is not my teaching.