Robert Siscoe and John Salza have repeated in their articles and interviews (we’ll see it again in their book) that St. Robert Bellarmine taught warnings are necessary to establish that one is a manifest heretic. For instance, Siscoe quotes the fourth opinion of Bellarmine and writes:
So according to St. Bellarmine, who bases his opinion on St. Paul, a heretic is considered to be manifestly obstinate after receiving two warnings. 
Again, in his reply to Cekada, Siscoe insists that Bellarmine taught that two warnings were necessary.
I’ve written several rebuttals to this assertion.  However, in another article against me, Siscoe tries to use John of St. Thomas as witness to his argument with Bellarmine. Siscoe writes:
According to John of St. Thomas, who studied Bellarmine at length regarding this question, and who spoke Latin fluently, Bellarmine was in agreement with Suarez that the pope must be declared incorrigible (declaratory sentence) by the Church before he loses his office. John of St. Thomas addressed this point in his treatise on the deposition of a heretical pope. He wrote:
“without qualification, the Lord Christ is the only superior with respect to the pope. And for that reason, Bellarmine and Suarez judge that the pope, by the very fact that he is a manifest heretic and has been declared incorrigible, is deposed immediately by the Lord Christ, not by some other authority of the Church.” 
So John of St. Thomas, who himself was a young contemporary of both Bellarmine and Suarez, and who wasn’t limited to reading a few quotations from Bellarmine posted on sedevacantist websites, states that Bellarmine agrees with Suarez in holding that a manifestly heretical pope must be “declared incorrigible” before being deposed immediately by Christ. 
What Siscoe doesn’t tell his readers is that John of St. Thomas criticizes Bellarmine for rejecting the need for two warnings. That’s right, the very person Siscoe (and Salza) uses as the primary source against sedevacantists, supports sedevacantists on Bellarmine.
John of St. Thomas wrote:
“Bellarmine objected that the Apostle [St Paul] says that we must avoid the heretic after two admonitions, that is to say, after he clearly appears pertinacious, before any excommunication and sentence of a judge, as St. Jerome says in his commentary, for heretics separate themselves by the heresy itself (per se) from the Body of Christ.
And here is his reasoning:
• A non-Christian cannot be Pope, for he who is not a member [of the Church] cannot be the head; now, a heretic is not a Christian, as commonly say the Fathers; thus, a manifest heretic cannot be Pope….
I answer [to Bellarmine] that the heretic should be avoided after two admonitions legally made and with the Church’s authority, and not according to private judgment. 
According to John of St. Thomas, Siscoe is wrong about Bellarmine.
John of St. Thomas got his information from Bellarmine’s De Romano Pontifice. If Bellarmine taught that the heretical pope needed to be declared incorrigible, then Siscoe would have cited Bellarmine, not John of St. Thomas. John of St. Thomas probably just lumped Suarez’s opinion with Bellarmine’s, because you won’t find Bellarmine saying a declaration is needed before the pope loses office.
John of St. Thomas is also saying that Bellamine’s position requires private judgment for which Salza/Siscoe condemn sedevacantists. How does private judgment fit in Bellarmine’s position if he taught that a declaration by the Church happens first?
Siscoe continues to mislead his readers when he quotes Wernz/Vidal as support for his argument against sedevacantism. Siscoe writes:
“It should also be noted, as Fr. Wernz S.J. observed, that the declaratory sentence of the crime “does not have the effect of judging a heretical pope, but of demonstrating that he has already been judged.” 
What Siscoe doesn’t tell his readers is that Wernz/Vidal taught that the opinion of Suarez, Cajetan, and John of St. Thomas is indefensible according to Bellarmine and Wernz/Vidal agree with Bellarmine. Wernz/Vidal write:
The fourth opinion, with Suarez, Cajetan and others [John of St. Thomas], contends that a Pope is not automatically deposed even for manifest heresy, but that he can and must be deposed by at least a declaratory sentence of the crime. “Which opinion in my judgment is indefensible” as Bellarmine teaches.
Finally, there is the fifth opinion – that of Bellarmine himself – which was expressed initially and is rightly defended by Tanner and others as the best proven and the most common. For he who is no longer a member of the body of the Church, i.e. the Church as a visible society, cannot be the head of the Universal Church. But a Pope who fell into public heresy would cease by that very fact to be a member of the Church. Therefore he would also cease by that very fact to be the head of the Church. 
The fifth and true opinion is utterly rejected by Siscoe and Salza who continue to misrepresent the popes, saints, and canonists on the issue.
Because the next quote is confused by Salza/Siscoe, a closer look at Pope Innocent III’s teaching is in order:
“The pope should not flatter himself about his power, nor should he rashly glory in his honour and high estate, because the less he is judged by man, the more he is judged by God. Still the less can the Roman Pontiff glory, because he can be judged by men, or rather, can be shown to be already judged, if for example he should wither away into heresy, because he who does not believe is already judged. In such a case it should be said of him: ‘If salt should lose its savour, it is good for nothing but to be cast out and trampled under foot by men.’” 
Notice that he qualifies his statement by saying “or rather, can be shown to be already judged.”
A pope who is already judged is not pope, that’s why he can be judged. Bellarmine said just that:
Therefore, the true opinion is the fifth, according to which the Pope who is manifestly a heretic ceases by himself to be Pope and head, in the same way as he ceases to be a Christian and a member of the body of the Church; and for this reason he can be judged and punished by the Church.
When does Bellarmine say the pope loses office: This is the opinion of all the ancient Fathers, who teach that manifest heretics immediately lose all jurisdiction… NOT AFTER WARNINGS OR DECLARATION BECAUSE heretics already before being excommunicated are outside the Church and deprived of all jurisdiction. For they have already been condemned by their own sentence, as the Apostle teaches (Tit. 3:10-11), that is, they have been cut off from the body of the Church without excommunication, as St. Jerome affirms… 
Salza/Siscoe actually reject what Bellarmine really says, and they reject “the opinion of all the ancient Fathers” all the while leading their readers to believe their private heretical opinion is shared by St. Robert Bellarmine and Wernz/Vidal. What’s funny is that Salza/Siscoe don’t even get John of St. Thomas right. Rather than admitting their errors, they will continue to attack sedevacantism and sedevacantists. What’s worse, they will continue to attack the Catholic papacy and undermine Christ’s promise to Peter!
 Sedevacanatist and the Manifest Heretic, The Remnant Online, POSTED: 3/27/13
 Definitive Proof that St. Robert Bellarmine Supports the Sedevacantist Position
 Answering a Sedevacantist Critic, The Remnant, Wednesday, March 18, 2015
 ON THE DEPOSITION OF THE POPE, Text of John of St. Thomas O.P.Translated from the Latin and annotated by Fr. Pierre-Marie O.P. (Avrillé. France) and published in Le Sel de la Terre [No. 90, Fall 2014] Translated from French to English by Fr. Juan Carlos Ortiz.
 Can the Church Depose an Heretical Pope?, The Remnant, Tuesday, November 18, 2014
 Jus Canonicum by the Rev F X Wernz S.J. and the Rev P Vidal S.J. (1938) Chapter VII. Translated by John Daly.
 Sermo 4
 De Romano Pontifici 30