Some persons have claimed that if a heretic is elected Pope, then he is not a valid Pope. And some have claimed that if a valid Pope falls into heresy, he ceases to be a valid Pope. Both claims are entirely false for several reasons. Other persons have refuted these false claims, but they were not able to give a clear and irrefutable theological reason as to why an elected Pope can certainly never be a heretic, and why no Pope can ever fall into heresy. They generally try to say that God would not permit such an event, but they cannot explain it further.
Election of a Heretic?
In order to be a valid Pope, three things are required:
1) a proper election,
2) his consecration as a Bishop (before or after his election)
3) his acceptance of the role of Pope of his own free will.
Suppose an unlikely event (this is hypothetical; it is not a prediction): a heretic is elected Pope. The election is of the proper form, and he is already a Bishop, but he is also a heretic (either secretly or openly). In order for the elected man to be a valid Pope, he must freely accept the role of Pope. When he does so, of his own free will, in that moment he becomes a valid Pope and in that very same moment he receives the gift of the fullness of the Sacred Magisterium, which is entirely incompatible with heresy. His acceptance of his election as Pope constitutes, in and of itself, an implicit repentance from heresy, and that implicit repentance combined with the gift of the infallible Sacred Magisterium immediately removes from him every trace of heresy. He might not call to mind his former heresy at that moment, yet it is vanquished from him.
And at a later time, when the issue that gave rise to his former heresy arises in his mind, he himself will find that he no longer adheres to that heresy. He will give due consideration to the teachings of the Church, and he will apply those teachings under the guidance of the Holy Spirit, regardless of his own personal holiness or lack thereof. He will no longer believe any truly heretical doctrine, even in his own mind or heart, nor can any Pope ever teach or believe a truly heretical doctrine.
See my article, The Three Charisms of the Sacred Magisterium, which further explains the fullness of the gift of the Sacred Magisterium, its three charisms, and its incompatibility with heresy.
Any Pope might teach erroneous points of doctrine, when teaching under the non-infallible ordinary Magisterium, if those points of doctrine are not essential to salvation, but such minor errors are not heresy. A Pope might have an erroneous personal opinion on a point of doctrine not yet definitively decided by the Magisterium, but again this is not heresy.
Can a Valid Pope Fall into Heresy?
Some persons have claimed that one Pope or another, historically, was validly elected, but after his election he fell into heresy by teaching a false doctrine and so he ceased to be a valid Pope. Other persons have claimed that this has not happened in the past, but that it is theoretically possible. And those who claim that it is not possible have not been able to explain why it is not possible, other than to say that God would not permit it.
In truth, all valid Popes are entirely unable to fall into any actual heresy. This includes every Pope, past, present, and future, holy or sinful, from the Apostle Peter, through all his valid Successors, even to the very last Pope before the Return of Jesus Christ. Now there have been and there will be antipopes, who are like wolves among the faithful, but such a man (or woman) was never a valid Pope. And as to women antipopes, no woman can ever be a valid Pope under any circumstances whatsoever, because every Pope must also be a Bishop and a woman can never be a valid Bishop. Even after Christ returns, He will not ordain women as Bishops, nor can there ever be a valid female Pope.
The Gift of the Magisterium
The reason that no valid Pope can ever fall into heresy is that the Pope possesses the fullness of the gift of the Sacred Magisterium. The Sacred Magisterium consists of three charisms:
1) the participation of each Bishop (including the Pope acting as a fellow Bishop) in the infallible Sacred Magisterium (e.g. in Ecumenical Councils and in the Ordinary Universal Magisterium)
2) the role of the Pope to offer authority, leadership, and guidance to his fellow Bishops as they exercise the Sacred Magisterium with him
3) the ability of the Pope to teach infallibly, by his own authority, without the consent or participation of his fellow Bishops (Papal Infallibility)
Only the Pope has the fullness of the gift of the Sacred Magisterium, for only the Pope can exercise all three charisms. Any Bishop can participate in the infallible Sacred Magisterium by teaching in communion with the other Bishops and the Pope. But only the Pope has the gift of the fullness of the Sacred Magisterium. The Pope is the seat of the infallible Sacred Magisterium, and its infallibility does not merely prevent him from teaching heresy, but also prevents him personally from falling into heresy. For heresy is entirely incompatible with the Sacred Magisterium, and the Sacred Magisterium is infallible.
Individual Bishops can fall into heresy, because they do not have the fullness of the Sacred Magisterium, but only a degree of participation in it. A heretic can be elected as Bishop, and his acceptance of the office of Bishop does not, in and of itself, vanquish his heresy. For individual Bishops, other than the Pope, are not the seat of the Sacred Magisterium, nor do they have the gift of the fullness of the Sacred Magisterium.
No Pope Can Fall Into Heresy
Some persons claim that a valid Pope can teach heresy, but that when he does teach heresy, he ceases to be a valid Pope. This idea might seem to protect the exercise of the Sacred Magisterium by the Pope from error. But this claim actually nullifies the infallibility of the Sacred Magisterium. It is as if they are claiming that only true teachings are infallible, or that it is only a teaching under infallibility if it is true. This version of ‘infallibility’ is useless.
We do not first evaluate a teaching, and then, upon deciding that it is true, reach the conclusion that the Pope is still a valid Pope and that the teaching is infallible. If such were the case, then the infallibility of a teaching would not rest upon the gift of the Sacred Magisterium, but upon the personal evaluation of each teaching by each member of the faithful. The teachings of the Sacred Magisterium are not infallible because they are certainly true, rather they are certainly true because they are taught by the infallible Sacred Magisterium.
For the faithful must believe all teachings that fall under the Sacred Magisterium. And it is certain that God has made the Sacred Magisterium infallible to such a full extent that no Pope can ever fall into heresy, neither in his teachings, nor in his own mind and heart. For the office and the person of the Pope is the seat of the Sacred Magisterium. Otherwise, the infallibility of the Sacred Magisterium would be founded on sand, rather than on the Rock that is the Successor to Peter.
A Papal Decree About Heretical Popes
Cum Ex Apostolatus Officio, by Pope Paul IV, February 15, 1559:
“6. Further, if ever at any time it becomes clear that any Bishop … or likewise any Roman Pontiff before his promotion or elevation as a Cardinal or Roman Pontiff, had strayed from the Catholic Faith or fallen into some heresy …then his promotion or elevation shall be null, invalid, and void… and they themselves who are thus promoted and assumed by that very fact, without any further declaration to be made, are deprived of every dignity, place, honor, title, authority, function and power….”
This papal decree would seem to prevent a heretic from being elected Pope. But it is problematic for a several reasons. First, this section (n. 6) of the document is one long complex sentence of over 300 words. The complexity of all the sentences in this document makes the meaning open to varying interpretations. Second, it states that if a man was a heretic before his election as Pope, his election is invalid even if he is elected with “the unanimous assent of all the cardinals.” Third, it states that no further declaration is needed for his election to be null and void. Fourth, it uses the phrase “if at any time” to indicate that even if it is discovered long after the election of a Pope that he was a heretic, his entire Papacy would still be invalid; this last measure places every Papacy in doubt, since we never have absolute knowledge about a Pope prior to his election.
And who would be qualified to determine that a newly-elected Pope is or was a heretic? If all the Cardinals agree in his election, then they certainly do not think that he is or was a heretic. So someone might claim that the Pope was a heretic, in opposition to most, if not all, of the Cardinals. And the document states that “no further declaration is needed” on the matter, so that it would seem to fall to each person to decide if the Pope ever was a heretic. Finally, it is not clear that the document excludes the idea that a Pope might fall into heresy after his election. Therefore, if at any time anyone disagrees with the doctrinal decision of a Pope, they might use this document as an excuse to call him a heretic and to depart from the Faith. (This has already happened with the sedevacantists and similar groups.)
Now in my considered theological opinion, no Pope can ever fall into heresy, since the gift of the infallible Sacred Magisterium resides in his person and office, not merely in his office. This does not mean that the Pope is personally infallible in all that he says and does as a private person, but it does mean that the Pope can never fall into heresy, even in his own private mind and heart. Also, if a heretic were ever elected as Pope, when he accepts his election of his own free will, then he has implicitly repented from his past heresy and so, by the same gift of the infallible Sacred Magisterium, he would immediately cease to be a heretic.
Therefore, by virtue of this truth, implicit in Sacred Tradition and Sacred Scripture, that the Pope cannot fall into heresy, and that a heretic who accepts his election as Pope immediately ceases to be a heretic, the declaration of Pope Paul IV concerning the validity of the election of a formerly heretical Pope is null and void. It is nullified by Sacred Tradition and Sacred Scripture, for no order under the temporal authority of the Church, even from the Roman Pontiff, retains its validity if it contradicts the infallible teaching of the spiritual authority of the Church, or of Divine Revelation. The temporal authority of the Church is subject to, and in the service of, its spiritual authority. And the spiritual authority of the Church is subject to, and in the service of, Divine Revelation.
Furthermore, no Pope can issue any decree under the temporal authority of the Church, no matter how strongly worded it might be, which would bind any or all future Popes without their consent. Certainly, a Pope can issue a decree which will retain its force until and unless a subsequent Pope amends or nullifies it. But to bind a future Pope irrevocably would be to reduce his authority. Each successive Pope would then have less authority than the previous Pope, due to the accumulation of irrevocable decrees under the temporal authority. But it is an indisputable doctrine of the Catholic Faith that each and every valid Pope has the same authority in spiritual and temporal matters as did Saint Peter the Apostle. Therefore, no Pope can bind future Popes using the temporal authority.
And decrees under the temporal authority of the Pope which seek to control the subsequent election of a future Pope have only a limited non-irreformable authority because the one who is elected immediately has authority to a greater degree than any such decree, and because the Cardinals and Bishops are entrusted with the temporal authority of the Church after the death or valid resignation of any Pope.
Now the spiritual teaching authority (the Magisterium) is another matter. When a Pope teaches infallibly under the spiritual authority of the Church, he is merely expressing a truth that was always found, at least implicitly, in Sacred Tradition or Sacred Scripture. All Popes are bound by all the teachings of Divine Revelation. Infallible teachings do not limit future Popes, they enlighten them. Thus, Popes who reign later have the advantage of the insightful teachings of past Popes, so that the Successors to Peter ever increase in knowledge. But they do not decrease in temporal or spiritual authority.
As a result of the above considerations, it is clear that the decree of Pope Paul IV was binding as concerns the Roman Pontiffs only during his administration as Pope. Subsequent Popes have changed the rules for electing the Pope, and have nullified all previous orders on that subject.
Universi Dominici Gregis
Pope John Paul II wrote the following in Universi Dominici Gregis:
“It is in fact an indisputable principle that the Roman Pontiff has the right to define and adapt to changing times the manner of designating the person called to assume the Petrine succession in the Roman See…. As determined above, I hereby declare abrogated all Constitutions and Orders issued in this regard by the Roman Pontiffs….”
The first part of this quote is from the introduction to the document, and the last part from its very end. Here Pope John Paul II has nullified (or abrogated) all past orders of past Popes related to the election of a Pope. Therefore, Pope Paul IV did not have the authority to bind all future Popes, even though his document states, “with this Our Constitution to be valid in perpetuity.” Here is an example of an error made by a Pope (namely, Pope Paul IV) under the temporal authority of the Church; for the temporal authority is always non-infallible. Pope Paul IV declared that his constitution would be valid in perpetuity, but it is not. Subsequent Popes were never bound by it. And Pope John Paul II specifically nullified all previous decrees, of all previous Popes, in so far as those decrees applied to the election of a Pope.
No Pope can ever fall into heresy because the Pope is the seat of the Sacred Magisterium and possesses all three of its charisms, in his person and office. If any heretic were validly elected as Pope, the act of his free will accepting his election would constitute an implicit repentance from any and all past heresies, and these heresies would then be immediately vanquished by the power of the Sacred Magisterium.
Pope Paul IV’s decree invalidating any election of a Pope, if that Pope is ever found to have been a heretic prior to his election, is limited in its own validity on that particular point to the length of his own Papacy. Future Popes have never been bound by that provision because the temporal authority of each Pope cannot tread upon, limit, or in any way diminish the temporal authority of future Popes, lest the See of Peter continually diminish in power and authority.