Br. Alexis Bugnolo tries to justify his agreement with the electors in choosing Jorge Bergoglio as pope by referring to Pope Eugene I who in the mind of Br. Bugnolo was a monothelite heretic before his election and then converted during his papacy. Br. Bugnolo refers to a book called A History of the Church that supposedly makes such a claim. I looked through this book and I could not verify Br. Bugnolo’s claim. Search the book yourself if you like and let me know if you find it. Nevertheless, the heresy of monothelism was solemnly condemned at the Third Council of Constantinople (680 – 681) which took place after the death of Pope Eugene I (+657). In regards to whether there has ever been a pope who fell into heresy, let us read the words of Archbishop John Baptist Purcell who recounted what happened during his attendance at the First Vatican Council:
“The question was also raised by a Cardinal, ‘What is to be done with the Pope if he becomes a heretic?’ It was answered that there has never been such a case; the Council of Bishops could depose him for heresy, for from the moment he becomes a heretic he is not the head or even a member of the Church. The Church would not be, for a moment, obliged to listen to him when he begins to teach a doctrine the Church knows to be a false doctrine, and he would cease to be Pope, being deposed by God Himself.
“If the Pope, for instance, were to say that the belief in God is false, you would not be obliged to believe him, or if he were to deny the rest of the creed, ‘I believe in Christ,’ etc. The supposition is injurious to the Holy Father in the very idea, but serves to show you the fullness with which the subject has been considered and the ample thought given to every possibility. If he denies any dogma of the Church held by every true believer, he is no more Pope than either you or I; and so in this respect the dogma of infallibility amounts to nothing as an article of temporal government or cover for heresy.”1
So it was answered during the First Vatican Council that there has never been the case of a heretic pope, thereby contradicting Br. Bugnolo’s claim. Now if it were possible for a pope to become a heretic, he would cease to be a member of the Church from the very moment that he fell into (public) heresy. Consequently, he could be deposed by a council of bishops since he would no longer be pope at the time of the deposition. So just as a pope who falls into heresy (if it were hypothetically possible) would be cease to be pope, a man who is a heretic could not be elected pope. A heretic is simply not a capable subject of receiving the form of the papacy. As Pope Pius XII taught in Mystici Corporis, the sin of heresy per se separates the heretic from the Church.2 Being separated from the Church, the heretic is no longer a member. Being no longer a member he could not be the head. To claim otherwise is to admit that the papal office can exist separated from the Church because the heretic being separated from the Church would nonetheless be pope. Hence, the claim is absurd.
Now Br. Bugnolo would tell you that a papal candidate has the right to be such if he has not yet been juridically declared a heretic by the Church. But is this a sufficient objection? No. The reason is that (public) heresy separates all bonds that the heretic has with the Church from the moment he falls into (public) heresy and not from the moment he is declared a heretic by the Church (read again the account of Archbishop Purcell). The fall into (public) heresy can be determined, as evidenced by the facts, even by the simple layman. Br. Bugnolo has himself admitted that Jorge Bergoglio was a heretic prior to the election that he, Br. Bugnolo, organized. In effect, therefore, he ought to conclude that, even if he truly believed that the convening of the election and the election process itself were valid, the very fact that a heretic was elected makes the validity of the elected as pope null and void.