What sort of heresy separates someone from the Church?

“There are many such distinctions in relation to heresy – and most are irrelevant.”

Image: Raphael, Disputa del Sacramento, Wiki Commons CC

Tradivox Catechism Review
Part I: How can we find the teaching of the universal ordinary magisterium?
Part II: What do the catechisms tell us about heretics and the Church?
Part III: How is the Church “visibly united in faith,” according to Cardinal Billot?
Part IV: Why is it essential that the Church is visibly united in faith?
Part V: What sort of heresy results in being outside the Church?
Part VI: What is the difference between an excommunicate and an open heretic?

Obj. I: Are we obliged to believe every person who calls himself a Catholic?
Obj. II: Should mistaken Catholics be called “material heretics”?
Obj. III: What is the state of a Catholic who submits to a false magisterium?

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For logistical reasons, Part V is being published in advance of Part IV. This should not impede understanding of the topic or points.

In this essay we will consider what type of heresy it is that separates a man from membership of the body of the Church.

In previous essays we have considered what it means for the Church to be visibly united in her profession of faith, and why this unity is an absolutely necessary property. Building on them, I shall continue drawing on the work of Louis Cardinal Billot – whose credentials I have already explained elsewhere – to explain the third thesis in this series:

3. Heretics, viz. those who visibly and consciously depart from this external profession of faith, by definition are not and cannot be members of the Church.

Let’s state clearly that for the question of membership, we are only considering heresy:

  • As it is a denial or doubt of a truth to be believed with divine and Catholic faith
  • As a human act, both in itself and as continuing as a state
  • Manifesting non-acceptance of the magisterium
  • As an open, public, knowable fact
  • Which thus separates a man from unity and from the Church by its own nature and definition
  • Regardless of moral culpability.

These are controversial issues. I offer these notes here as my best understanding of the teaching of Cardinal Billot, which seems to me to make a lot of sense. I welcome criticism of this piece.

Let’s start by defining heresy, and then address these points.

What is heresy?

According to St Thomas Aquinas, in the Summa Theologica, heresy is “a species of unbelief, belonging to those who profess the Christian faith, but corrupt its dogmas.”[1]

Canon 1325 gives us a definition of a heretic:

§ 2. After the reception of baptism, if anyone, retaining the name Christian, pertinaciously denies or doubts something to be believed from the truth of divine and Catholic faith, [such a one is] a heretic […].[2]

What are the things “to be believed,” mentioned in this canon? Vatican I tells us:

“All those things are to be believed with divine and Catholic faith which are contained in the Word of God, written or handed down, and are proposed by the Church either by a solemn judgment or by her ordinary and universal magisterium to be believed as divinely revealed.”[3]

Therefore, a heretical proposition is one that contradicts such truths; and heresy itself is the pertinacious doubt or denial of such truths, by one who is baptised.

But how should we understand the difference between heresy as a proposition, the affirmation of such a proposition, and a proper act of heresy?

What distinguishes heresy from a mistake?

Mere confusion or slips of the tongue are not “pertinacious” doubts or denials of the truths mentioned. One who doubts a particular dogma – but only because he does not know that it is dogma – is hardly pertinacious: he is just confused.

Something more is needed to make such a doubt or denial an act of heresy.

Billot explains what this is by defining, “according to the origin of the term and the constant sense of all tradition,” who is a heretic:

“[A baptised man who] does not accept the rule of what must be believed from the magisterium of the Church, but chooses from somewhere else a rule of belief about matters of faith and the doctrine of Christ; whether he follows other doctors and teachers of religion, or adheres to the principle of free examination and professes a complete independence of thought, or whether finally he disbelieves even one article out of those which are proposed by the Church as dogmas of Faith.”[4] (Emphasis added)

“Pertinacity” refers to the consciousness and voluntariness of the non-acceptance of the magisterium as the rule of faith.[5]

Some might ask: What about internal heresy? Heresy as a sin or a crime? Formal or material? Notorious or occult? Warnings? Culpability? Sentencing? Penalties?

There are many such distinctions which we could draw in relation to heresy – and most are irrelevant to the question of membership. Billot’s treatment abstracts from all such things, stating that in relation to membership:

“[It is a question] purely and simply of heresy that has the power to cut a man off from the visible body of the Church, and is directly opposed to the external profession of the Catholic religion.” [6]

This might seem tautological at first, but only if one lacks a grasp of what the Church is, and how she is united in faith. Note also that he talks about heresy having the power to cut a man off from the Church; not excommunication as a punishment for heresy.

In Billot’s treatment – using similar terms to Leo XIII in Satis Cognitum – membership is intimately and inextricably linked to the Church as a visible unity of faith. He writes:

“[If] the unity of the profession of faith, which is dependent on the visible authority of the living magisterium, is the essential property by which Christ wanted His Church to be adorned forever, it follows clearly that those cannot be part of the Church who profess differently from what its magisterium teaches. For then there would be a division in the profession of faith, and division is contradictory to unity.”[7] (Emphasis added)

In light of this, we can understand the significance of Cardinal Billot’s observation that “the notion of heresy” is not just the denial or doubt of dogma alone, but also requires “the rejection [or non-acceptance] of the rule of the ecclesiastical magisterium” by a baptised person who still claims to be a Christian.[8]

All the following points about the effects of heresy are rooted in the nature of the Church as a society which is necessarily and visibly united in faith, as taught by this magisterium.

Human acts

Discussions about heresy and membership become confused due to a lack of unanimity of terms. For example, should it be treated as a sin, or a crime?

For these reasons, let’s abstract from such things and consider heresy solely as a human act.

“Being a human act” is logically prior to an act’s goodness or sinfulness. Sagües defines an act in the broad sense, as “any activity of man either elicited or commanded by the will whether interior, such as a thought or desire, or exterior, such as a word or deed.” (Emphasis added.)[9] In a negative sense, an omission can also be an act.

McHugh and Callan define a human act as follows:

“Those acts are called human of which a man is the master, and he is master of his actions in virtue of his reason and his will, which faculties make him superior to non-human agents that act without reason and freedom.”[10]

These moralists then state that this excludes acts committed without the control of the mind (i.e. by one who is inadvertent, insane, distracted, drunk or under extreme fear or anger, etc) or the will. They also exclude:

“[N]atural acts (such as sleeping) and spontaneous acts (such as stroking one’s beard absent-mindedly), [which] are not voluntary acts.”[11]

In other words, a human act is one for which the agent is responsible, as it proceeds from his intellect and will. It excludes absent-minded, non-voluntary acts; and includes omissions in so far as these are also voluntary.

The object which specifies the human act of heresy is the doubt or denial of dogma and the non-acceptance of the Church’s magisterium as the rule of faith – for whatever reason, with whatever level of culpability, and without reference to the penalty entailed.

This abstracts from whether the agent incurs any guilt or merit as a result of his act. A given act might well be a sin in an objective sense, whilst remaining completely inculpable for the agent – despite also remaining a true human act on his part.

As an example of inculpable non-acceptance, we could consider those baptised men who are raised outside the Church, and who have no idea that they even should accept the Roman Catholic Church’s magisterium. While such persons might not be culpable of moral fault, it remains true that they consciously and voluntarily accept some other rule of faith than that of the Roman Catholic Church – or no rule at all.

In other words, even their inculpable rejection of the magisterium is a true human act, and is truly pertinacious in the sense described above.

For the purposes of membership, we are considering heresy solely in this way, as a human act – not as an act which is subjectively sinful or criminal. Although, in the concrete, such an act will have an objective moral value, this way of thinking allows us to abstract from a lot of confusion around culpability, canonical processes and condemnations.


Some acts can be considered, not only in themselves, but also as continuing as a state.[12] An act can morally continue as a state “by default,” in the sense that it is unrevoked by the agent.

As an example: a mortally sinful act continues in a moral sense, as “a state of mortal sin”, until the act is removed. More prosaically, the state of “being outdoors” is that of one who has gone outside (or was never inside), and it endures until he goes inside.

We could define the state of heresy as that of a baptised man who has committed an act of heresy (as defined above), which state continues until it is removed.

When it is open and public, this state itself is a separation from the visible unity and profession of faith – and therefore from the Church. Secret or internal heresy would have different effects, as would ambiguous cases. These examples are not relevant to the question of membership.[13]

A state can be “renewed” by further or even habitual acts of the same kind – or by other acts which are less clear, but can only be explained as proceeding from someone in a particular state.

Such acts – even those which are less clear – may be a key way in which the state of heresy is manifested. A state of heresy may sometimes be observable even if the “smoking gun” act of heresy – the first act of heresy, whence the state arose – is unknown or unclear. Such a state, and such less clear acts, may even clarify an agent’s prior and previously ambiguous acts.

Cardinal Newman wrote along these lines about the Church of England. He said that it was not necessary to pinpoint which of many acts or events actually consummated the Church of England’s separation from the Catholic Church – that separation was clear enough, without knowing when it began.[14]

He wrote that all the Church of England’s various acts and events, combined with its general “animosity against Catholicism” (which “is conscious, deliberate, and hearty, the coagulate of bitter experiences and of festering resentments”) are sufficient proof that the Church of England is in a state of separation from the Catholic Church. This is so, he said, whichever act or event might have been the one that actually caused this state.[15]

Note again, that these points are based on the Church of England itself, and not on condemnations, declarations or excommunications. In other words, a man of judgment can look at a gestalt and form a correct and morally certain conclusion about the state of things, without reference to the precise moment at which this state of separation arose.

And obviously, any remaining uncertainty about which moment or act gave rise to this state would not somehow show that a separation had not taken place.

It is obvious that what Newman says of the heretical (and schismatic) body of the Church of England can also apply, at least sometimes, to individuals.

To summarise, abstracting from sinfulness or culpability, a past act of heresy “morally continues” as a state of ongoing rejection or non-acceptance of the magisterium, until it is removed by a sufficiently public profession of the faith and acceptance of the true rule of faith.

This is confirmed by the practice of the Church, which requires a public act of abjuration, and profession of faith from converts from heresy. Following a sufficiently public act, we could say that the state ends – even if other penalties may remain, depending on the situation.

Such a profession must be exterior, clear and open – because it is removing an exterior, clear and open state of heresy. Let’s consider these qualities in relation to heresy.

Exterior and clearly contrary to unity of faith

Billot’s treatment focuses solely on that type of heresy which, by its own nature, separates a man from the visible unity of the Church.[16] As we saw above, only exterior acts can rupture a visible unity. Secret and internal acts cannot do this. 

These acts include words, actions or omissions which reveal heresy, as already defined. Even some non-verbal acts can be sufficiently clear – Fr Charles Augustine says that even wearing certain clothes can be sufficient, “if they are distinctive and notorious signs or proofs of infidelity, heresy or apostasy.”[17]

We can leave aside any ambiguous verbal and non-verbal acts which do not actually manifest non-acceptance of the magisterium. Billot states that the visibility of the Church is tolerant of a small number of merely doubtful members and ambiguous cases:

“This visibility also deals with the whole group considered all together, and not each person taken singly… it is sufficient that there be certitude about most of them.”[18]

All this said, we can ask: how open must this exterior act be?

Open, Public, Notorious, Manifest

Any exterior act admits of varying degrees of “publicity” (“publicness” or visibility).

According to Billot, membership of the Church requires that “the social bond of the unity of Faith not be broken by formal heresy or even by merely material heresy.”[19]

Because the social bond is visible and external, Billot’s states:

“Since only that heresy which turns into public profession brings about this impediment, it must be said that only notorious heretics are excluded from the body of the Church.”[20]

Some persons equate “notoriety” with “notoriety of law,” insisting that a heretic is only “notorious” once he has been warned and declared as such by an authority, or once he has confessed his guilt in a legal form.

But this is false. It neglects the category of “notoriety of fact,” and is contrary to the sense of what is being discussed. I will address this in the objections, along with other equivocations around terms. In the meantime, let’s recall the centrality of the Church’s unity of faith in Billot’s treatment, wherein any public profession that sufficiently breaks that visible and external bond of unity is “notorious” heresy in the relevant sense.[21]

Some persons also claim that anyone calling himself a Catholic remains a Catholic, and cannot be called more than an “occult” (secret) heretic or suspect of heresy until declared otherwise – no matter how evidently and outrageously deliberate his heresy might be.

There are indeed some words of Billot which could suggest such an idea, which I will address in the objections. But for now, let’s state that the point of warnings and declarations is to make manifest the rejection or non-acceptance of the magisterium and distinguish it from an innocent mistake. But such warnings are not always necessary if the non-acceptance is already publicly known, especially if it cannot be hidden by evasion or claims to the contrary.

Wrangling over declarations, mere verbal claims and so on is a diversion. The question is one of fact, one of reality:

Do this man’s acts or state clearly manifest a doubt or denial of a truth of faith, and a non-acceptance of the magisterium?

If they do, then it is an act or state of heresy in the relevant sense.

Abstracted from both culpability and good faith (formal and material heresy)

Heresy is indeed a grave sin, but this gravity has no bearing on the topic. This is why Pope Pius XII teaches:

“For not every sin, however grave it may be, is such as of its own nature to sever a man from the Body of the Church, as does schism or heresy or apostasy.”[22] (Emphasis added)

This is seen even more clearly when we remember that the conclusion holds even when we abstract from moral culpability. Let’s see why.

Catholics who are mistaken in good faith, or who express a heretical idea without advertence, are not rejecting the authority of the magisterium. On the contrary, such persons accept that authority and are either mistaken about what it teaches, or express it wrongly without advertence.

A few exceptions and ambiguous cases like this do not jeopardise the visible unity of the Church: they are resolved by an actual and visible submission to the magisterium.

Such ambiguous cases are sometimes imprecisely called “material heretics,” but this language is rejected by Billot:

“[M]aterial heretics are those who labor under invincible ignorance about that same Church, and in good faith choose a different rule to guide them.”[23]

To return to the definition, a heretic is one who does not accept the magisterium as his rule of faith. Formal heretics are culpable for their non-acceptance, being aware of the Church’s authority; material heretics are in good faith – perhaps not having had it sufficiently proposed to them, or perhaps thinking that Canterbury, Constantinople or the Scriptures are the true rule of faith.

But both classes of heretics deliberately and consciously do not accept this magisterium, and thus they are visibly separated from the Church’s visible unity of faith. Therefore, without regard for culpability, neither formal nor material heretics (according to this terminology) are members of the Church. Wrangling over the material-formal distinction is missing the point.

This is why Billot states – in words which many might find surprising – that the whole doctrine of the membership of the Church pertains to material heresy, rather than formal heresy:

“[W]ith regard to real incorporation into the visible Church of Christ of which we are now speaking the thesis does not make any distinction between formal and material heretics, but understands everything according to our notion of material heresy […] which alone is proper and genuine heresy.”[24] (Emphasis added)

He explains further, citing the authority of the Fathers:

“[T]he Fathers teach sufficiently that even material heretics are outside the visible Church when they exclude all those who have been seduced by heresiarchs and belong to their congregations in any way, and the Fathers make no distinction between those who are participants in their crimes, and those who possibly in good faith follow those who are outside.”[25]

I have already addressed the meaning of the word “pertinacity” above, and will return to it in the objections.

If we consider a good-faith Anglican, his rejection or non-acceptance of the magisterium may or may not be imputed as a sin, but it nonetheless remains a deliberate human act or state of heresy – accompanied, evidently, by a state of non-membership. He is also a schismatic, but that is a separate topic.

In this sense, despite his good faith, he is pertinacious.

In the objections, I also address the unusual (but today, common) situation of Catholics who accept a false rule of faith whilst thinking that it is the magisterium of the Catholic Church. In brief, like Catholics mistaken about individual dogmas, these persons cannot be considered even material heretics by this fact alone. More argumentation would be needed to reach such a conclusion.

Some object to Billot’s use of the term “material heresy” – but in most cases, this is a merely verbal disagreement, and the conclusions end in the same place.

All this illustrates the irrelevance of objections based on the inability of us to read hearts, make judgments about the internal forum, and to know whether someone “really” is a heretic. All that is needed here is moral certainty – that certainty which is based on the normal mode of human conduct. This is expressed by St Robert Bellarmine on the very subject of heresy, which recapitulates the point of Cardinal Newman above:

“[M]en are not bound to, or cannot scrutinize hearts; but when they see someone acting in a heretical way, they simply judge that he is a heretic, and they condemn him as a heretic.”[26]

To summarise again, the question is: Does this man accept or not accept the magisterium of the Roman Catholic Church as his rule of faith?

If he openly does not do so, even if he is in good faith, then he is a heretic in the relevant sense, and not a member of the Church.


As mentioned at the start, I offer these notes as my best understanding of Cardinal Billot’s treatment of heres and membership. I welcome any criticism or explanations as to why either he or I are wrong.

It seems that those who have committed a sufficiently open act of heresy, or who are in a sufficiently open state of heresy, which clearly manifests their failure to profess the Faith and to accept the Church’s magisterium as their rule of faith, are heretics in the sense relevant to membership.

This also applies to those who are clearly and openly in a state in which they do not accept this rule of faith – this state is the “smoking gun”, even if we cannot find the exact “bullet,” or the moment at which it was fired.

Those whose heresy I have described here are separated from the Church’s visible unity of faith by the nature of their acts and state; and they are thus not members of this Church. This is true whether or not they have been condemned by authority – and excommunication is a wholly different matter.

And so we arrive at the last of the four theses we have been examining in this series – which is a mere corollary to all this. I shall treat it briefly in the next part.

Tradivox Catechism Review
Part I: How can we find the teaching of the universal ordinary magisterium?
Part II: What do the catechisms tell us about heretics and the Church?
Part III: How is the Church “visibly united in faith,” according to Cardinal Billot?
Part IV: Why is it essential that the Church is visibly united in faith?
Part V: What sort of heresy results in being outside the Church?
Part VI: What is the difference between an excommunicate and an open heretic?

Obj. I: Are we obliged to believe every person who calls himself a Catholic?
Obj. II: Should mistaken Catholics be called “material heretics”?
Obj. III: What is the state of a Catholic who submits to a false magisterium?


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[1] St Thomas Aquinas, Summa Theologica, II-II, Q11 A1. (and for UK readers)

[2] The 1917 or Pio-Benedictine Code of Canon Law, in English Translation with Extensive Scholarly Apparatus, trans. Dr Edward Peters, Ignatius Press, San Francisco, 2001

[3] Vatican I, Dei Filius, Ch. 3, “Concerning Faith”, Dz 1792, trans. John Daly

[4] Louis Cardinal Billot, Tractatus de Ecclesia Christi, Tomus Prior, Prati ex Officina Libraria Giachetti, Filii et soc, 1909, p 291. Trans. Fr Julian Larrabee.

[5] Billot refers to pertinacity in passing, but his treatment of the overall topic of heresy seems to treat pertinacity more along the lines of the first (and apparently obsolete) definition of the word “pertinacious” given in the Oxford English Dictionary: “1. Of a state or thing: persistent, continuing; spec. (of a disease) resistant to treatment. Obsolete. […] 2. Persistent or stubborn in holding to one’s own opinion; resolute; obstinate. Usually as a negative quality.” The currency or obsolescence of words in the Oxford English Dictionary and the English language are not the main point: the point is to illustrate how Billot treats this concept in relation to heresy. In any case, the second, “current” definition defines pertinacious as “resolute,” whilst also suggesting that it does not always imply something negative. The point here is that it is a human act which is deliberate and voluntary.

[6] Billot 617 Translation by Novus Ordo Watch, available here.

[7] Billot 294

[8] Billot 293

[9] Joseph F. Sagües, S.J ‘On Sins’, in Sacrae Theologiae Summa IIB, edited by Biblioteca de Autores Cristianos, originally published in 1955, translated by Fr Kenneth Baker SJ, Keep the Faith, 2014. No. 823

[10] John A. McHugh OP and Charles J. Callan OP, Moral Theology – A Complete Course Based on St. Thomas Aquinas and the Best Modern Authorities (UK readers), B Herder, London, 1958. no. 23.

[11] McHugh and Callan, no. 33-4

[12] Sagües No. 817d

[13] It is true that a minority of theologians believe that even secret heretics are not members. I will leave the explanation and defence of that opinion to those who wish to embrace it. But note that even this minority opinion does not undermine these conclusions about open heretics..

[14] John Henry Cardinal Newman, Essays Critical & Historical, Vol. 2, Longmans, Green, and Co., London, 1907, p 106. (And for UK readers)

[15] Ibid. 103.

[16] He is not alone here: as an example, Emil Dorsch abstracts from these distinctions in the same way and also mentions that an excommunication does not pertain to the nature heresy or schism themselves:

“Excommunication is indeed inflicted by law as an ecclesiastical penalty for sins of heresy or schism, whether notorious or occult; but here we shall not consider heresy or schism in this respect – rather we shall consider them only in that which is connected with heresy or schism by their own nature, abstracting from the dispositions of the law.”

In a similar way, the theologian Wilmers gives the following thesis, and clarifies accordingly:

“Proposition III: Manifest heretics are not, in act and properly, members of the Church. […]

“This discussion does not concern the penalty of excommunication imposed on all external heresy, but rather the exclusion that follows heresy by its very nature.” (Emphasis added)

Emil Dorsch, S.J. De Ecclesia Christi, in Institutiones theologiae fundamentalis, Oeniponte, 1928. p 489. Available at Internet Archive. Guilelmo Wilmers, De Christi Ecclesia Libri Sex, 1897. Liber VI, Caput I, Articulus II, Propositio 111, n. 397, p 634. Ratisbonae, Friderici Pustet, S. Sedis. Apost. et S. Rit. Congr. Typogr.

[17] Charles Augustine, A Commentary On The New Code Of Canon Law, Volume 6, Herder Book Co., St Louis MO, 1918, pp 329-336. (UK readers). Available at Internet Archive.

[18] “This visibility also deals with the whole group considered all together, and not each person taken singly; for no one certainly would say that we should believe by divine faith that this or that particular person is truly a member of the Church, and not just in appearance. […] [T]his visibility certainly does not require that there be no doubt about anyone at all about whether he be a member of the Church or not, but it is sufficient that there be certitude about most of them.” Billot 279, translated by Fr Julian Larrabee

[19] Billot 291

[20] Billot 291

[21] Billot 291

[22] Pius XII, Encyclical Mystici Corporis Christ, 1943, n. 23. Available at: https://www.vatican.va/content/pius-xii/en/encyclicals/documents/hf_p-xii_enc_29061943_mystici-corporis-christi.html

[23] Billot 292

[24] Billot 292

[25] Billot 295

[26] St Robert Bellarmine, Controversies of the Christian Religion, trans. Fr Kenneth Baker SJ, Keep the Faith Press, USA, 2016, 983.

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