Has the Church changed its teaching on oaths [Mt 5:33-37]?


Hi, I posted the following in the Ask an Apologist section, but I reckoned it was a bit long, so it may not get answered so I said I’d post here too. Hope you guys can help.


I’m an agnostic, interested in early Christianity and lately have been delving into some modern Catholic theology also. Glad you guys are open to new registrations again. I was hoping you guys could shed some light on something I have been pondering for a while.

I’ve been doing a lot of research on how the commands of the Sermon on the Mount were observed in the early Church and by far the deepest I have dug regards oaths [Matthew 5:33-37 cf James 5:12].

In the works of the earliest orthodox ecclesiastical writers, the saying is deemed to be a total prohibition of all oaths. This can be seen in the works of Justin Martyr, Irenaeus of Lyons, Clement of Alexandria, Origen, Tertullian, Cyprian of Carthage, Gregory Thaumaturgus, Eusebius, Hilary of Potiers, Basil the Great, Ambrose, Chromatius, Jerome, Gregory Nazianzen, Gregory Nyssa, Epiphanius, John Chrysostom, Benedict of Nursia, Salvian, Basil of Seleucia, Didymus the Blind, Rufinus of Aquileia, Isaac the Syrian and Caesarius of Arles (expansive, not exhaustive, citations available). The prohibition can also be found in a plethora of early anonymous/pseudonymous orthodox works (eg. Didascalia, Pseudo-Clementine Homilies, Acts of Pilate, Pseudo-Hippolytus etc.) as well as all throughout the Martyrdom genre (though a strain of attempted, yet dismissed compromise can be found; see Acts of Apollonius, 6 cf. Tertullian, Apology, 32: Swearing is unlawful, even by Christ, will not swear by Genius of Caesar, but will compromise to swear by safety/health of Caesar/ by God that we love Caesar) and though the teachings of those outside of the orthodox traditions such as Ptolemy the Gnostic and Pelagius.

A typical example of the interpretation is found in Justin Martyr, First Apology, 16.5:

And with regard to our not swearing at all, and always speaking the truth, He enjoined as follows: “Swear not at all; but let your yea be yea, and your nay, nay; for whatsoever is more than these comes of evil.”

Yet towards the end of the fourth century and the beginning of the fifth, this interpretation began to change. The motive for the change seems to stem from both the societal side (Romanisation of Christianity and the use of oaths in civil and daily life) and from the theological side (wide acceptance of Augustine’s Anti-Pelagian writings, which contained a defense of oath taking, based upon Paul and the necessity of swearing).

This interpretation of complete prohibition of all swearing is no longer present in Catholic teaching, nor even is the teaching of Augustine “if you are compelled to swear, know that it comes of a necessity arising from the infirmity of those whom you are trying to persuade of something; which infirmity is certainly an evil” (On the Sermon on the Mount, 51) cf. Aquinas, (S.T., IIa-IIæ, Q. 89 A.2) as this would condemn the Church’s infirmity, e.g. The Oath of Fidelity, Can 380. The Haydock commentary is typical of modern Christian thought on the matter, Catholic, Orthodox and mainstream Protestant alike: “Swear not at all. We must not imagine that here are forbidden all oaths.” The idea of a total prohibition is usually associated with heretics and schismatics, yet the unanimous teaching of the early Church is vastly ignored, barring a small number of critical commentaries and historical studies.

While my primary interest is the study of the early Church, I have been tying it in with modern theology lately. I cannot help but feel that this heavily goes against the typical mantra of “doctrine does not change,” and that it makes the fourth precept of the Oath against Modernism: “I sincerely hold that the doctrine of faith was handed down to us from the apostles through the orthodox Fathers in exactly the same meaning and always in the same purport,” rather ironic. I was hoping a seasoned theologian could rise to the challenge.

The only thing close to dealing with this issue within official Catholic documentation and without, in the Catholic apologist blogosphere is from Pius VI’s condemnation of the Synod of Pistoia, Auctorem fidei, LXXV, which really only condemns the teaching which “proceeds to condemn the oaths which the ecclesiastical curia… adopted”.

The teaching which says that in the happy days of the early Church oaths seemed so foreign to the model of the divine Preceptor and to the golden simplicity of the Gospel that “to take an oath without extreme and unavoidable need had been reputed to be an irreligious act, unworthy of a Christian person,” further, that “the uninterrupted line of the Fathers shows that oaths by common consent have been considered as forbidden”; and from this doctrine proceeds to condemn the oaths which the ecclesiastical curia, having followed, as it says, the norm of feudal jurisprudence, adopted for investitures and sacred ordinations of bishops; and it decreed, therefore, that the law should be invoked by the secular power to abolish the oaths which are demanded in ecclesiastical curias when entering upon duties and offices and, in general, for any curial function, -false, injurious to the Church, harmful to ecclesiastical law, subversive of discipline imposed and approved by the Canons.

Interestingly, elsewhere I have argued the opposite of the Synod of Pistoia, which attempted to reform the Church by reverting to a simpler, stricter Church akin to early Christianity, by arguing that since change can and has occurred, more doctrinal changes may be possible. See here reddit.com/r/Catholicism/comments/3rvuvq/free_friday_can_you_play_a_devils_advocate_to/cws2w0u.

Hope you can shed some light.


Very fascinating topic. I’ve never researched this before, but to get started I used the Church Fathers Search Engine to search for examples of common words used in oaths, such as “God is my witness” and “before God.” (It is also interesting to search for the term “vows.”) I found that several of the Fathers you cited against oaths seem to have made oaths right in their writings. For example:

St. Irenaeus - “I can bear witness before God, that if [St. Polycarp] had heard any such thing, he would have cried out, and stopped his ears.” source

Anonymous - “I testify before God and your brotherhood, that before all of you have I preserved a clean conscience.” source

Eusebius of Caesarea - “before God Almighty and our Lord Jesus Christ do we witness, being able by proofs to show and to convince you, that, even in times past, such has been our belief and preaching.” source

St. Athanasius - “The Lord is witness, and His Anointed is witness, I have never spoken evil of your Piety before your brother Constans.” source

And: “God is my witness, that on account of their persecution I have not been able to see even the parents whom I have.” source

And: “I have all confidence to answer for my conduct, in the first place before God, and also before your Piety, for that I did not flee and desert my people.” source

St. Dionysius - “I speak also before God, and He knows that I lie not: it was not by my own choice, neither was it without divine instruction, that I took to flight.” source

St. Cyprian - “I have always called [her] Etecusa—God is my witness—because she gave gifts for herself that she might not sacrifice.” source

Clementine Homilies - “I take to witness heaven [and] earth…that I shall always be obedient to him who gives me the books of the preachings.” source

Anonymous - “I wish to plead before God about the race of the Christians.” source

St. Basil of Caesarea - “God is my witness. I have heard them myself.” source

And: “I call God and man to witness that all this is ill done, and a breach of the law of the Church.” source

And: “Remember the good profession which you witnessed before God.” source

Note: I think that one is particularly important because it is evidence that oath-taking was an institutional part of the early Church in the form of the vows of consecrated religious.

St. Jerome - “I call God to witness that I am no flatterer.” source

And: “I call Jesus and his saints, yes and the particular angel who was the guardian and the companion of this admirable woman to bear witness that these are no words of adulation and flattery but sworn testimony every one of them borne to her character.” source

Rufinus - “God is my witness how truly I can say that I have kept silence on many more points than I have brought forward.” source

Anonymous - “I call heaven and earth to witness, that if God permitted the enemy to rage as much as he desires, all men should have perished long ere now.” source

St. John Chrysostom has an interesting commentary on an oath made by St. Paul in Scripture. source

Sulpitius Severus - “I recently saw a certain man (God is my witness), not without a feeling of shame at the spectacle, seated on a lofty throne.” source

Now, you have said that you have “expansive, not exhaustive, citations available” from all the Fathers you cited against oaths, many of whom appear to use oaths in the list above. I would like to see your citations, but perhaps you should post them somewhere else and then link to them here, because such extensive documentation might break the forum rules. (No double posts, etc.)

But if the example you gave is indicative, it seems questionable. St. Justin Martyr does two things: he cites the text of Scripture that says not to swear at all and says that Christians therefore do not swear at all. His contribution is nearly identical to the text itself. If the text itself uses hyperbole, or if it somehow allows for swearing in the name of Christ under certain circumstances, then seemingly St. Justin’s text could use hyperbole too, or allow for swearing as long as it is “done right”. And maybe it is the same with the other Fathers you have citations for. I would like to see the citations you have before judging, of course, but the fact that so many of them show up on both my list and yours leads me to suspect that they thought some swearing in the name of Christ was permissible even though they seem to comment on this passage that Christians do not swear at all.

I hope that helps. God bless!


Thank you for a well-researched, documented and relevant reply. While I would generally prefer to give a more condensed argument, I often find that when I do, I will get little more than: “Paul swore in his epistles!” I am currently researching the topic for a project and I want a section to tie in into modern theology, so any and all answers help.

My list of source material can be found here: awaywiththeatheists.blogspot.ie/2015/11/on-oaths-normal-0-false-false-false-en.html

Unfortunately, my reply ran away with me, so I posted it on my personal blog here: awaywiththeatheists.blogspot.ie/2015/11/reply-to-dmar198.html

Thanks again


Thanks again

Your welcome. :slight_smile: Thank you for posting your references so thoroughly.

The force of your argument is: if an ecclesiastical writer swore an oath, they could not have believed the saying of Jesus to prohibit all oaths.

That sounds close to accurate.

Yet we cannot say this a priori holds true.

But we can hold it to be true if there is evidence that their oaths did not conflict with their beliefs.

The practice does not affect the teaching, otherwise we are approaching Donatism.

Practice does Reflect doctrine. Lex Orandi, Lex Credendi: if my understanding of that phrase is correct, it means that Church practices cannot be in contradiction with the faith. Perhaps the writings of the Fathers, including the oaths therein, are an example of Lex Orandi.

only the commentary on the teaching itself or allusions to it will show how they understood it.

I don’t think that’s accurate. As a counter-example, the early Church frequently used religious images, as has been shown through research on early Christian sepulchers, chalices, catacombs, and early church buildings, among other things. This is evidence that they did not interpret the Bible as forbidding images. In the same way, I think a case can be made that if the early Christians used oaths in religious ways, this is evidence that they did not interpret the Bible as forbidding oaths. And some of the examples I gave are, in my estimation, religious oaths, as are some other examples I’ve thought of since then.

A distinction of oaths and vows must be made…they cannot be equated like you have done with the reference of Basil concerning a vow of Virginity

Some vows involve oaths. I think there is evidence that the vow of consecrated religious involved some kind of oath. There was certainly some kind of public ceremony made before bishops. St. Ambrose mentions that faraway women came to Italy to be consecrated at the hands of bishops (Concerning Virginity Book 1 Chapter 11) and preserves part of the ceremony used when his sister made her vows before the pope: newadvent.org/fathers/34073.htm

I think it is noteworthy that the translation contains the word “sacrament” in reference to this solemn ceremony: “[God] will confer the pure sacrament of virginity on you.” As you may know, sacrament was one of the Latin words for oath. It appears from this that Marcellina and the other virgins publicly manifested some kind of intent not to have sex, and the public religious ceremony was intended to witness to the truth of her intention. To me, that is at least equivalent to an oath, especially in light of the language used.

BTW St. Ambrose is not the first to indicate that vowed virgins were consecrated by Church authorities. St. Cyprian’s Letter to Pomponius connects virgin’s vows to Church authority in the matter of enforcement. Tertullian also suggests some public aspect of consecrated virgins: “virgins [are] not compelled to be veiled, [but] at all events [those who] voluntarily [become] so should not be prohibited.” source

Many of your quotes are assertions with a “God is my witness” thrown in. … It is precisely this unnecessary and “evil habit”…[which] is so condemned by both ancient and modern commentators…

The ones by Sulpitius Severus and St. Cyprian seem more open to that objection, but I’m not willing to concede that they were. Certainly the witness called upon by St. Basil, St. Athanasius, and Rufinus seem like more serious matters to this reader.

In modern commentators Jesus cannot have meant all oaths, so surely he meant all habitual oath taking

That is, of course, one of several modern interpretations. It is my opinion that Jesus used hyperbole to convey the message that swearing is dangerous, not evil, and that some of the Fathers adopted this hyperbole while also swearing when appropriate.

The fourth century presents a different picture: while the idea that Jesus prohibited all oaths is maintained, the theology surrounding it begins to polarise.

To me, all the examples I’ve read in context are compatible with the view that the Fathers were adopting a hyperbole used by Jesus to convey that swearing is dangerous. But I haven’t read all your references yet, and I am particularly intrigued by Chrysostom and Nazianzen.

I searched Chrysostom for the phrase “to witness” at this link. In one place he appears to interpret a command of St. Paul as a command to the Church to have people take oaths. On the text “put them in remembrance, charging them before the Lord,” St. John Chrysostom comments: “It is an overawing thing to call God to witness what we say, for if no one would dare to set at nought the testimony of man when appealed to, much less when the appeal is to God. If any one, for instance, entering into a contract, or making his will, chooses to call witnesses worthy of credit, would any transfer the things to those who are not included? Surely not. And even if he wishes it, yet fearing the credibility of the witnesses, he avoids it. What is charging them before the Lord? He calls God to witness both what was said, and what was done.” source

Nazianzen makes an oath about St. Basil using this form: “I speak before God as my witness” source

Perhaps you would say that is a “lesser oath” and he condemns himself, but his subject matter seems pretty serious in that case. He seems to be lauding St. Basil for serious reasons and wants his audience to know that he really means this, it’s not just rhetoric.


Thank you for posting your references so thoroughly.

No problem, you’re welcome. I’ve been at this a few months. I have a few more in untranslated Greek, and a whole tract on oaths from Ephraem in untranslated Syriac (which I have no hope of translating, might have to call in a few favours).

Again my reply ran overboard. So: Part 1.

This is evidence that they did not interpret the Bible as forbidding images. In the same way, I think a case can be made that if the early Christians used oaths in religious ways, this is evidence that they did not interpret the Bible as forbidding oaths.

It is is true that we can infer that [most] early Christians did not forbid image due to their use. The question is: do early witnesses provide us with commentary forbidding the use of icons as we see with oaths? They vastly do not. Therein lies the difference with regards oaths. Commentary on oaths is filled with prohibition.

As you may know, sacrament was one of the Latin words for oath.

It’s just not that relevant. I’ll just let Daniel Kennedy handle it: “The word “sacrament” (sacramentum), even as used by profane Latin writers, signified something sacred, viz., the oath by which soldiers were bound, or the money deposited by litigants in a contest. In the writings of the Fathers of the Church the word was used to signify something sacred and mysterious, and where the Latins use sacramentum the Greeks use mysterion (mystery).”

I think there is evidence that the vow of consecrated religious involved some kind of oath… It appears from this that Marcellina and the other virgins publicly manifested some kind of intent not to have sex, and the public religious ceremony was intended to witness to the truth of her intention. To me, that is at least equivalent to an oath, especially in light of the language used.

Again, not to be confused with an oath. It, like a creed or sacrament, is a profession. Not an oath. See: Catholic Encyclopedia: Virginity

The resolution of virginity is generally offered to God under the form of a vow. The counsel of virginity is expressly given in the New Testament; first in Matthew 19:11-12, where Christ, after reminding His disciples that besides those who are unfit for marriage by nature, or by reason of a mutilation inflicted by others, there are others who have made the same sacrifice for the kingdom of heaven, recommends them to imitate these. “He that can take, let him take it.” Tradition has always understood this text in the sense of a profession of perpetual continence.

Though there is certainly some evidence to suggest that the command described was also taken literally by some: see: Caner

I mean seriously, in the same said treatise that you cite, Ambrose compares, yet does not equate the Christian Creed with the military oath (Book 3, 4.20) and commentating on Herod’s oath, declares: “The Lord therefore in the Gospel bids us not to swear at all.” (Book 3, 6.28) How then, when he says as such, can we expect Ambrose to permit oaths without further explanation?


Part 2.

To me, all the examples I’ve read in context are compatible with the view that the Fathers were adopting a hyperbole used by Jesus to convey that swearing is dangerous.

This argument is really stretched.
I ask: Where is the hyperbole in…

Origen: “And with respect to the precepts enjoined in the Gospels, no doubt can be entertained that very many of these are to be literally observed, as, e.g., when our Lord says, But I say unto you, Swear not at all.”

Tertullian: “Christ prescribes that there is to be no swearing.”

Cyprian: “…you are compelled to swear, which is not lawful.”

Gregory Thaumaturgus: “…by all manner of means to avoid an oath, especially one taken in the name of God.”

Eusebius: “Basilides, …] declared that it was not lawful for him to swear at all, for he was a Christian.”

Basil of Caesarea: “Swearing is absolutely forbidden”

Gregory Nazianzen: “How much more ascetic is the Gospel than the Law! You shall not forswear yourself is the Law; but you are not to swear at all, either a greater or a lesser oath, for an oath is the parent of perjury.”

John Chrysostom: “Again he who swears, says He, even if he fulfil his oath, does the works of the wicked one.”

I ask how can these be considered exaggerations? Are we to say they meant, it is ok to swear if you think it is necessary? Would they have said the same with regard to the previous command from the Mount, concerning divorce?

If you want to see hyperbole viz. the condemnation of oaths, Chrysostom often goes above and beyond.

The sword is not so piercing as the nature of an oath! The sabre is not so destructive as the stroke of an oath! The swearer, although he seems to live, is already dead, and has received the fatal blow.

Comparing oaths to murder? Now that’s hyperbole!

Nazianzen makes an oath

First: Does he? What exactly is he testifying to? That he prefers Basil? Would his preference have been questioned had he not added that God was his witness? Is it necessary? Is it an oath? I’m not so sure, but for the sake of the argument let’s say it is.

Second: Does Gregory consider it an oath? This is the more important question. He certainly condemns oaths: “you are not to swear at all, either a greater or a lesser oath, for an oath is the parent of perjury”. However; in a apologetic context, trying to remove the stain of the blatant oaths in Paul, comments that ““God is my witness,” and “God knows :” those words are not an Oath, but an assurance of things unbroken." So we certainly have context for him not considering his own words an oath. However, let’s say he did swear, and that he considered it swearing, for the sake of argument.

Third: If it is an oath: again I ask, does Nazianzen’s action as a priest, putting an oath in his writing, make his later condemnation of oaths as a bishop in an episcopal oration and in a directed polemic against swearing null and void? Does it lessen the meaning because he once swore? Must then the same be said when Augustine comments on sexual immorality due to his own history with sexual immorality?

In one place [Chrysostom] appears to interpret a command of St. Paul as a command to the Church to have people take oaths.

Does he? It appears to me that he does not attempt to implement what he says on others. I sincerely doubt this is his intention. To share my favorite quote

“But you, if you heed nothing else, reverence at least that book, which you reach forth in putting the oath; and open the Gospel, which you take in hand when you bid swear; and when thou hear what Christ there declares concerning oaths, shudder and desist! What then does He there say concerning oaths? But I say unto you, Swear not at all. And do you convert the Law which forbids swearing into an oath. Oh, what contempt! Oh, what outrage!”

This concept, that the early Christians prohibited all oaths, is one that is not often commented on in modern history books. As F.D. Bruner points out: “… the history of the interpretation of this Command has been a history of evasions.” Few wish to admit that this command was taken literally in the first few centuries, as it would have theological implications on how it should be interpreted now. However; those who have commented say quite simply that “In the earliest Church, especially in the East, almost without exception, Jesus’ Command against oaths was taken literally.” (Bruner p. 234). Later: “‘The entire tradition of the Great Church since the early Middle Ages almost unanimously set Matt 5:33-37 aside and accepted oaths, even though often with a bad conscience.” (Luz, p. 319). See bibliography here: Oaths

Even the Church seems to admit this. In Auctorem fidei, LXXV, Pius VI seems only to condemn the idea that the fact that the early Church forbade oaths should be a reason to change Church practices regarding oaths.

Again my main question being: How should this be considered? Doctrinal development or doctrinal change?


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