Sedevacantism is the belief that the chair (sede) of Peter is vacant (vacante) meaning that the Catholic Church has no pope. The vast majority of Sedevacantists believe that Pope Pius XII was the last legitimate pope of the Church and that subsequent popes, by nature of their heresy, have separated themselves from the Church and have been consequently ineligible to become pope. This monograph will explore the Sedevacantist position in light of the Catholic understanding of heresy with reference to canon law and Church theologians and demonstrate how Sedevacantism is an unsound position.
Body and Soul of the Church
Before delving into the issue of heresy it is important to understand the nature of the Church and the internal and external bonds which comprise membership of this Church - i.e. the Body and Soul of the Church.
The Catechism of Pope St Pius X describes the Body of the Church (external spiritual bonds) as consisting in, "... her external and visible aspect, that is, in the association of her members, in her worship, in her teaching-power and in her external rule and government."
The Catechism of Pope St Pius X describes the Soul of the Church (internal spiritual bonds) as consisting in, "... her internal and spiritual endowments, that is, faith, hope, charity, the gifts of grace and of the Holy Ghost, together with all the heavenly treasures which are hers through the merits of our Redeemer, Jesus Christ, and of the Saints."
A person can be united either perfectly or imperfectly to either the Body or Soul of the Church.
To be perfectly united to the Body of the Church one must be a formal member of the Catholic Church. A person is imperfectly united to the Body of the Church when they sincerely desire to become a member of the Church, for example, a person who is in the process of converting to the Church. In order to achieve salvation a person can be either perfectly or imperfectly united to the Body of the Church. Salvation is able to be achieved by imperfect union with the Body by virtue of Baptism of desire or Blood.
To be perfectly united to the Soul of the Church one must be in possession of the virtues of faith, hope and charity and living in the state of grace. Imperfect union with the Church is when one has faith, but is living in the state of mortal sin. Salvation, therefore, can only be obtained by perfect union with the Soul of the Church.
Now we shall explore the nature of heresy and the different kinds of heresy.
Material heresy is, simply put, when one holds a belief which is contrary to Catholic doctrine. Material heresy however, is not necessarily sinful and does not by itself sever one from either the Body or Soul of the Church. If the belief is genuinely held without knowledge that said belief is contrary to Catholic doctrine, it is not necessarily sinful and consequently one is still internally and externally united to the Church.
Formal heresy takes one of two forms; internal formal heresy or external formal heresy.
Formal heresy, just as material heresy, requires that one hold a belief which is contrary to Catholic doctrine. This heresy becomes formal heresy (internal) when that belief is held with pertinacity of will - i.e. when a person wilfully and knowingly denies or doubts Catholic doctrine. Formal heresy is a grave sin against faith. St Thomas Aquinas expanded upon this point when he said:
Just as mortal sin is contrary to charity, so is disbelief in one article of faith contrary to faith. Now charity does not remain in a man after one mortal sin… Therefore it is clear that such a heretic with regard to one article, has no faith in the other articles, but only a kind of opinion in accordance with his own will. - Summa Theologica Part II-II
This shows clearly that when one denies an article of the faith, they sever themselves from the Soul of the Church, however, they are not necessarily severed from the Body of the Church. Only external formal heresy severs a person from the Body of the Church.
External formal heresy is when one manifests this internal heresy publically and is officially declared a heretic, either by the authority of the Church or the individual themselves. In order to publically declare their own heresy a person must clearly and publically deny a dogma of the Church. It is this external act which severs one from both the Body and Soul of the Church.
Fr Suarez, a Jesuit canonist, when discussing this point notes:
Faith is not absolutely necessary in order that a man be capable of spiritual and ecclesiastical jurisdiction and be able to exercise true acts which demand this jurisdiction …. The foregoing is obvious, granted that, as is taught in the treatises on penance and censures, in case of extreme necessity a priest heretic may absolve, which is not possible without jurisdiction.
The Pope heretic is not a member of the Church as far as the substance and form [soul] which constitute the members of the Church; but he is the head as far as the charge and action; and this is not surprising, since he is not the primary and principal head who acts by his own power, but is as it were instrumental, he is the vicar of the principal head, who is able to exercise his spiritual action over the members even by means of a head of bronze; analogously, he baptizes at times by means of heretics, at times he absolves, etc., as we have already said. - De Fide
Fr Marie Dominique Bouix, another Jesuit canonist, also explored this point:
Faith is not necessary for a man to be capable of ecclesiastical jurisdiction and that he might exercise true acts which require such jurisdiction. (…) Moreover, the power of orders, which in its way is superior, can remain without faith, that is, with heresy; therefore ecclesiastical jurisdiction can do so too. (…) To the argument that, not being a member of the Church [the soul], the heretical Pope is not the head of the Church either [the body] (…) one can give the following answer: I concede that the Pope heretic is not a member and head of the Church in so far as the supernatural life which commences by faith and is completed by charity [the soul], by which all the members of the Church are united in one body supernaturally alive; but I deny that he might not be a member and head of the Church as far as the governing power [the body] proper to his charge. - Tract on the Pope
St Robert Bellarmine, whom many Sedevacantists claim legitimise their position, also looked at the matter when discussing occult heretics (occult heresy, it should be noted, is defined as formal heresy):
Occult heretics are still of the Church, they are parts and members… therefore the Pope who is an occult heretic is still Pope. This is also the opinion of the other authors whom we cite in the book De Ecclesia. …the occult heretics are united and are members although only by external union; on the contrary, the good catechumens belong to the Church only by an internal union, not by the external. - De Romano Pontifice Book II
All of this goes to show that, while anyone - including a pope - may be in heresy, they are not necessarily separated entirely from the Church and consequently do not lose offices that they hold.
Next it is time to explore how canon law applies to the situation. Because the Sedevacantist movement has its roots prior to the promulgation of the 1983 Code of Canon Law the 1917 Code will be explored as it was in force at the time of Pope John XXIII's election to the papacy.
"Whoever in any manner willingly and knowingly helps in the promulgation of heresy, or who communicates in things divine with heretics against the prescription of Canon 1258, is suspected of heresy."
"One suspected of heresy who, having been warned, does not remove the cause of suspicion is prohibited from legitimate acts; if he is a cleric, moreover, the warning having been repeated without effect, he is suspended from things divine; but if within six months from contracting the penalty, the one suspected of heresy does not completely amend himself, let him be considered as a heretic and liable to the penalties for heretics."
Canon 2315 builds upon Titus 3:10-11, which states:
 A man that is a heretic, after the first and second admonition, avoid:  Knowing that he, that is such a one, is subverted, and sinneth, being condemned by his own judgment.
The Douay-Rheims commentary builds upon the phrase 'By his own judgement':
 "By his own Judgement": Other offenders are judged, and cast out of the Church, by the sentence of the pastors of the same church. Heretics, more unhappy, run out of the church of their own accord, and by doing so, give judgement and sentence against their own souls.
As has already been demonstrated, in order to be separated from both the Body and Soul of the Church, one must be an external formal heretic - i.e. a formal and manifest heretic. However it is necessary that one is declared so by the Church authority or by one's self. As canon 2316 shows, even when it may seem that a man is manifest heretic by our own opinion, he is regarded by the Church to only be suspect of heresy and consequently the Church must go through the process for declaring someone a heretic as outlined in canon 2315. It needs to be noted that none of the post-Vatican II popes have ever been through any official process from the Church towards declaring heresy, save for our current Pontiff, Pope Francis, who has been presented with the first step - the dubia.
The question which then arises is how to know if formal heresy has become manifest and who may have the power to declare this.
St Robert Bellarmine, when looking at the opinion of St Cajetan (who believed that manifest heresy was not enough to depose a pope and that only the Church authority can do this) stated:
The argument from authority is based on Saint Paul, who orders that the heretic be avoided after two warnings, that is, after showing himself to be manifestly obstinate. - De Romano Pontifice Book II
This clearly demonstrates that he believes two official warnings are necessary before one becomes a manifest heretic - warnings which have not been given to any of the post-Vatican II popes.
When exploring St Robert Bellarmine's point, Fr Pietro Ballerini, a renowned 18th century canonist and theologian, looked at who is responsible for warning a pope:
The Cardinals, who are his counselors, can do this; or the Roman Clergy, or the Roman Synod, if, being met, they judge this opportune... Therefore the Pontiff who after such a solemn and public warning by the Cardinals, by the Roman Clergy or even by the Synod, maintained himself hardened in heresy and openly turned himself away from the Church, would have to be avoided, according to the precept of Saint Paul. - De Potestate Ecclesiastica
This clearly shows that it is not any person who has the authority to warn a pope of heresy, but those within the Church authority. It is interesting to note that Pope Francis has been presented with the dubia, the next step being a public and formal correction which may be considered a warning as discussed by St Paul.
St Robert Bellarmine, when declaring that manifest heretics automatically lose their office, did not explain how we may know when formal heresy becomes manifest. The 19th Century theologian Sebastian Smith however, spoke on the matter in Elements of Ecclesiastical Law:
Question: Is a Pope who falls into heresy deprived, ipso jure, of the Pontificate? Answer: There are two opinions: one holds that he is by virtue of divine appointment, divested ipso facto, of the Pontificate; the other, that he is, jure divino, only removable. Both opinions agree that he must at least be declared guilty of heresy by the church, i.e., by an ecumenical council or the College of Cardinals. The question is hypothetical rather than practical.
St Francis de Sales also spoke on this matter:
We do not say that the Pope cannot err in his private opinions, as did John XXII; or be altogether a heretic, as perhaps Honorius was. Now when he is explicitly a heretic he falls ipso facto from his dignity and out of the Church, and the Church must either deprive him, or as some say, declare him deprived, of his Apostolic See, and must say as St. Peter did: Let another take his bishopric – Acts 1. - The Catholic Controversy
St John of St Thomas also spoke on the subject declaring that even manifest heresy requires a declaration by the Church:
So long as he [a pope] has not become declared to us juridically as an infidel or heretic, be he ever so manifestly heretical according to private judgment, he remains as far as we are concerned a member of the Church and consequently its head. Judgment is required by the Church. It is only then that he ceases to be pope as far as we are concerned.
It is undeniable that Pope Francis is poor pontiff and a material heretic. It is also undeniable that Popes Paul VI, John Paul II and Benedict XVI have made heretical statements or actions, but this does not prove that it is anything more than material heresy, which is not enough to deprive one of the office of pope. This monograph has shown that there is a definite process which must be followed when determining if the pope - or anyone else - is a formal and manifest heretic. Not every lay person or priest has the authority to declare anyone a heretic, let alone to declare the pope a heretic. The process laid down by St Paul, which has been extrapolated by various theologians and canonists and promulgated in the 1917 Code of Canon Law must be followed before a pope can be declared a formal and manifest heretic. Only then is a pope separated from both the Body and Soul of the Church and ipso facto lose the Petrine Office.