What constitutes heresy?

In a couple of places online, including here I have heard that heresy involves obstinate disobedience against a dogma of the Catholic faith. In other places, I have seen people assert that heresy can involve obstinate disobedience against infallible doctrines as well. However, I have not been able to find anyone asserting the latter who was an apologist, theologian, or a canon lawyer, and so I am not certain if it is true.

If anyone here is any one of those things and could answer or could direct me somewhere where I could get an answer, it would be very much appreciated. I am upset that the Ask an Apologist option is no longer available to choose as a category.

Specifically, I am wondering if disagreements with the Church on artificial birth control, women priests, abortion, and remarriage without annulments would be considered to be at odds with either dogma or doctrine (either infallible or fallible). (I am guessing that all except artificial birth control are dogma, since references to them can be found in the sacred scriptures, but I would like to hear from somebody else.)

Thank you.

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I think you will find some answers here

Two statements of assent are in the professio fidei:

  • “With firm faith, I also believe everything contained in the word of God, whether written or handed down in tradition, which the Church, either by solemn judgment or by the ordinary and universal Magisterium, sets forth to be believed as divinely revealed.”
  • "I also firmly accept and hold each and everything definitively proposed by the Church regarding teaching on faith and morals”.

These are all matters of faith and morals:

  • artificial birth control is immoral (intrinsically)
  • abortion is immoral (intrinsically)
  • sterilization is immoral (intrinsically)
  • that priests must be male is a necessary requirement for valid Holy Orders (See Ordinatio Sacerdotalis)
  • that the freedom to marry is a necessary requirement for valid Matrimony

Actually, an apologist, a theologian etc. aren’t a guarantee, at least in my part.

On the contrary a misfit can be reliable if he indicates all the sources of a question in the Magisterium.

Magisterium in turn highlights the Scripture’s sources, if it is possible.

Often it’s more quick to search in www.vatican.va or in Catechism 1992 or in Canon Law 1983, than looking for an expert.

It depends on the specific problem and our ability to search through Magisterium’s documents.

Thank you for posting that document, but I have a question.

The document you site states in point 5:

The first paragraph states: “With firm faith, I also believe everything contained in the word of God, whether written or handed down in tradition, which the Church, either by solemn judgment or by the ordinary and universal Magisterium, sets forth to be believed as divinely revealed”. The object taught in this paragraph is constituted by all those doctrines of divine and catholic faith which the Church proposes as divinely and formally revealed and, as such, as irreformable…These doctrines require the assent of theological faith by all members of the faithful. Thus, whoever obstinately places them in doubt or denies them falls under the censure of heresy, as indicated by the respective canons of the codes of canon law.

In point 6, where it refers to the second statement, “The second proposition of the professio fidei states: ‘I also firmly accept and hold each and everything definitively proposed by the Church regarding teaching on faith and morals’.” it states the following:

Such doctrines can be defined solemnly by the Roman pontiff when he speaks “ex cathedra” or by the college of bishops gathered in council, or they can be taught infallibly by the ordinary and universal Magisterium of the Church as a “sententia definitive tenenda”. Every believer, therefore, is required to give firm and definitive assent to these truths, based on faith in the Holy Spirit’s assistance to the Church’s Magisterium and on the Catholic doctrine of the infallibility of the Magisterium in these matters. Whoever denies these truths would be in the position of rejecting a truth of Catholic doctrine and would therefore no longer be in full communion with the Catholic Church.

Why doesn’t it use the same language as point 5 if it’s saying this is heresy? In other words, why not use the word heresy if it is in fact heresy and not simply mortal sin to deny these things? Being in a state of mortal sin does remove one from full communion with the Catholic Church without excommunicating the person latae sententiae or otherwise. So, if Cardinal Ratzinger (now Pope Benedict) wanted to convey this as actual heresy, why wouldn’t he just come out and say so?


Heresy is the obstinate post-baptismal denial of some truth which must be believed with divine and catholic faith, or it is likewise an obstinate doubt concerning the same”

I recommend reading this entire Catechism section including that on doubt and incredulity.



You said yes, but which one is it? And does dissent with any of those things constitute actual heresy that results in excommunication latae sententiae?

You are welcome.

They are different classes:

  1. CIC Canon 750 § 1 addresses divinely revealed things to be believed by divine and catholic faith – common Catholic adherance.
  2. CIC Canon 750 § 2 addresses everything set forth definitively on faith and morals.


Sometimes the language is confusing, and so it is good to have an expert to interpret it. Also, there are conflicting reports as to what does and does not constitutes heresy, possibly because the language is confusing (see my response to Vico). So, it can be good to have someone with some kind of authority weigh in. Especially about something this serious.

In Canon 1371, what constitutes a “just penalty”?

In Canon 1436 § 1, what constitutes “legitimately warned”?

And so is what I was asking about heresy or isn’t it? And would a person who persisted in believing such things who meets all the other criteria for excommunication actually be excommunicated latae sententiae?

A just penalty could be suspension from office or a censure.

Canon 1436 that you ask about is in the eastern canon law so applies to eastern Catholics. Legitimately warned means by one in authority with regard to their sui iuris Catholic church, for example by your bishop. See CIC Can. 1371 for warning that applies to Latin Catholics.

A latae sententiae excommunication censure is in the Latin canon law, but not in the eastern canon law, so it does not apply to all Catholics. There are many conditions for this censure.

Can. 1321 §1. No one is punished unless the external violation of a law or precept, committed by the person, is gravely imputable by reason of malice or negligence.
§2. A penalty established by a law or precept binds the person who has deliberately violated the law or precept; however, a person who violated a law or precept by omitting necessary diligence is not punished unless the law or precept provides otherwise.
§3. When an external violation has occurred, imputability is presumed unless it is otherwise apparent.

Can. 1322 Those who habitually lack the use of reason are considered to be incapable of a delict, even if they violated a law or precept while seemingly sane.

Can. 1323 The following are not subject to a penalty when they have violated a law or precept:
1° a person who has not yet completed the sixteenth year of age;
2° a person who without negligence was ignorant that he or she violated a law or precept; inadvertence and error are equivalent to ignorance;
3° a person who acted due to physical force or a chance occurrence which the person could not foresee or, if foreseen, avoid;
4° a person who acted coerced by grave fear, even if only relatively grave, or due to necessity or grave inconvenience unless the act is intrinsically evil or tends to the harm of souls;
5° a person who acted with due moderation against an unjust aggressor for the sake of legitimate self defense or defense of another;
6° a person who lacked the use of reason, without prejudice to the prescripts of cann. 1324, §1, n. 2 and 1325;
7° a person who without negligence thought that one of the circumstances mentioned in nn. 4 or 5 was present.

CIC Can. 1364 §1. Without prejudice to the prescript of can. 194, §1, n. 2, an apostate from the faith, a heretic, or a schismatic incurs a latae sententiae excommunication; in addition, a cleric can be punished with the penalties mentioned in can. 1336, §1, nn. 1, 2, and 3.

Yes to all of them.

Latae sententiae excommunication is a high bar. A person would have to meet all the criteria.

There is much written about this in the jurisprudence of the Church.

If you have these doubts or dissent, then it is incumbent upon you to (a) assent in faith and (b) continue to study and learn so that you can root out the errors in your position and © not spread or teach the errors.

But what if at one point someone did and now realizes the errors of their ways? Supine ignorance of the existence of a penalty might exist in a lot of cases, especially in the age of the internet where information is so readily available. Would that person now need to get the excommunication lifted?

You have to realize:
there is a difference between heresy, and the Church’s legal judgment against someone of “heretic”.

This is where many Catholics over-use the word (and over-use it unjustly, by definition) against anyone who does not accept some tenet of the faith.
A lay person should never be calling someone a heretic or accusing someone of heresy. It’s not appropriate and it’s counterproductive.

That’s not obstinate post baptism denial of the truths of the faith.

And as I said, you’d have to overcome all the criteria that preclude it, and ignorance is one of them.

Doesn’t mean people aren’t ignorant, both of church teaching and of church law.

Please stop.

Excommunication isn’t something you can accidentally incur.


Even if someone warned them at one point that it was heresy and excommunicable and the person did not make a solid effort to find out whether the one who told them was telling the truth?

Even then.

If you need to seek the counsel of your pastor, do so. Posting generalities on the internet are not going to help you. If you have something specific that concerns you, speak to your pastor about it.

What do you all think of this article by canon lawyer Edward Peters?: https://www.catholicworldreport.com/2019/01/30/on-excommunicating-andrew-cuomo-for-heresy/

It seems to imply that having and publicly propounding beliefs about things like homosexual marriage, abortion, artificial birth control does not constitute heresy.

I see what you’re saying, but I suppose in that case, it would no longer be “accidental”. Still though, you’re saying they would be ignorant. To me, that kind of ignorance would seem to be supine, and they would still be held responsible.

What I think is that none of us are canon lawyers and trials for heresy are very technical things.

No that isn’t what he is saying at all.

Again: go talk to your priest if you have a concern.

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