Did Early Christians Forbid Swearing Oaths?
Early Christians mostly taught that believers should not swear oaths in ordinary speech. Justin Martyr, Irenaeus, Clement of Alexandria, Tertullian, Origen, the Didache, and the Apostolic Constitutions all connect Christian speech with Jesus’ command, “Swear not at all.” Some writings also discuss false swearing, rash swearing, and hard cases, but the main direction is clear: speak truth plainly and keep your word. The Bible passages most often used here are Matthew 5:34, James 5:12, and related texts about false oaths.
113 early-church witnesses · 187 source quotations · compared with Scripture
What did early Christians believe about swearing Oaths?
Early Christians usually taught that believers should not swear oaths in daily speech and should keep their word without them. Justin Martyr, Irenaeus, Clement of Alexandria, Tertullian, Origen, Lactantius, the Didache, and the Apostolic Constitutions all point in that direction, often quoting Jesus’ command, “Swear not at all.”
Some writers also made a limited distinction between rash or false swearing and lawful court or covenant language, so the evidence is not perfectly uniform on every edge case. But the main line is broad and early: Christian speech was meant to be plain, truthful, and free from careless oaths. Many more early Christian quotations, Bible passages, and source links are gathered below so you can study the evidence for yourself.
Key Takeaways
- Most early Christian teachers said believers should not swear oaths in normal speech.
- Justin Martyr, Irenaeus, Clement of Alexandria, Tertullian, Origen, and the Didache all use Jesus’ command against swearing.
- Some later texts allow limited oath language in special cases, but they still warn strongly against false or careless swearing.
- The steady ideal is simple speech: yes means yes, and no means no.
Questions Answered by the Sources
Did early Christians teach that believers should not swear oaths?
The selected sources repeatedly say Christians should not swear, or should avoid swearing as a normal habit. Several writers cite Jesus' command to speak simply and truthfully instead of multiplying oaths.
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Justin Martyr, The First Apology Direct teaching
And with regard to our not swearing at all, and always speaking the truth, He enjoined as follows: “Swear not at all;
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Irenaeus, Against Heresies: Book II Direct teaching
...es not only not to hate people, but also to love their enemies; and instructed them not only not to swear falsely, but not even to swear at all. He told them not only not to speak evil of their neighbors, but not even to call anyone "Raca" and "fool," declaring that otherwise, they were in danger of hell-fire. They were told not only not to strike, but even, when they themselves were struck, to offer the other cheek to those who mistreated them; and not only not to refuse to give up the property of others, but even if their own were taken, not to demand it back from those who took it. They were instructed not only not to harm their neighbors or do them any evil, but also, when they themselves were mistreated, to be patient and to show kindness towards those who harmed them, and to pray for them, so that through repentance they might be saved—so that we should in no way imitate the arrogance, lust, and pride of others. Since He, whom these people boast of as their Master, and of whom they claim had a soul greatly better and more refined than others, did indeed command certain things to be done as good and excellent, and certain things to be avoided not only in their actual perfor
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Clement of Alexandria, The Stromata (Miscellanies) Direct teaching
... man whose character has been proved in this kind of godliness is far from being ready to lie or to swear an oath. For an oath is a final statement made by calling on the divine name. How can someone who is already faithful show himself unfaithful, as if he needed an oath? Should not his life itself be a sure and final oath? He lives, walks, and shows the trustworthiness of what he says by a steady and reliable life and speech. And if the wrong belongs to the judgment of the person who does and says something, and not to the suffering of the person who has been wronged, then he will neither lie nor swear falsely, and so do wrong in relation to the Deity, knowing that by nature the Deity cannot be harmed. Nor will he lie or commit any transgression for the sake of his neighbor, whom he has learned to love, even if that person is not a close friend. Therefore, even more, he will not lie or swear falsely for his own sake, since he could never willingly be found doing wrong to himself.
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Origen, Against Celsus Supporting witness
I do not know, moreover, how Celsus came to hear about elephants being faithful to oaths, or about their great devotion to our God, and the knowledge they have of Him. For I know many wonderful things that are told about the nature of this animal and its gentle character. But I do not know that anyone has spoken of its keeping oaths, unless he gives that name to its gentle character and to its keeping agreements, so to speak, once they have been made between it and man. But that statement itself is also false. For although it happens rarely, it has sometimes been recorded that, after seeming tame, elephants have broken out against men in the most savage way, have committed murder, and have therefore been condemned to death because they were no longer useful. And after this, in order to prove, as he thinks, that the stork is more pious than any human being, he brings forward the stories told about that creature's filial affection in bringing food to its parents to support them. We must reply that storks do this, not from regard for what is proper, and not from reflection, but from natural instinct. The nature that formed them desired to show, among irrational animals, an example tha
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Lactantius, The Epitome of the Divine Institutes Direct teaching
but he will not even swear, lest at any time, either by necessity or through habit, he should fall into perjury.
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Didache, The Teaching of the Twelve Apostles Direct teaching
...at has been conceived. You shall not covet the things of your neighbor, Exodus 20:17. You shall not forswear yourself, Matthew 5:34. You shall not bear false witness, Exodus 20:16. You shall not speak evil. You shall bear no grudge. You shall not be double-minded or double-tongued, for to be double-tongued is a snare of death. Your speech shall not be false or empty, but fulfilled by deed. You shall not be covetous, nor rapacious, nor a hypocrite, nor evil disposed, nor haughty. You shall not take evil counsel against your neighbor. You shall not hate any man. But some you shall reprove, and concerning some you shall pray, and some you shall love more than your own life.
What did early Christians say about false swearing and perjury?
The sources strongly condemn false swearing, perjury, and vain or careless oaths. They present these as sins that bring guilt and judgment, not as acceptable Christian speech.
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Justin Martyr, The First Apology Supporting witness
Regarding our refusal to swear and our commitment to speaking the truth, He instructed us: “Do not swear at all; but let your yes mean yes, and your no mean no; for anything more than this comes from evil.” He also encouraged us to worship God alone: “The greatest commandment is, You shall worship the Lord your God, and Him only shall you serve, with all your heart, and with all your strength, the Lord God who made you.” When a man approached Him saying, “Good Master,” He replied, “There is none good but God only, who made all things.” Let those who do not live as He taught be recognized not as Christians, even if they verbally profess the teachings of Christ; for it is not those who merely profess, but those who act, who shall be saved, according to His words: “Not everyone who says to Me, Lord, Lord, shall enter into the kingdom of heaven, but he who does the will of My Father in heaven. For whoever hears Me and obeys My teachings, hears Him who sent Me. Many will say to Me, Lord, Lord, have we not eaten and drunk in Your name, and done wonders? And then I will say to them, Depart from Me, you workers of iniquity. There will be wailing and gnashing of teeth, when the righteous sh
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Irenaeus, Against Heresies: Book IV Supporting witness
...h their brother without cause will be in danger of judgment." And, "It has been said, You shall not swear falsely. But I tell you, Do not swear at all; but let your response be Yes, yes, and No, no." And other statements like these. For all these do not imply an opposition to or overturning of the principles of the past, as Marcion's followers strongly assert; rather, they show a fulfilling and extension of them, as He Himself declares: "Unless your righteousness surpasses that of the scribes and Pharisees, you will not enter the kingdom of heaven." What did the excess referred to mean? First, we must believe not only in the Father but also in His Son now revealed; for He is the one who leads man into fellowship and unity with God. Next, we must not only speak but also act; for they spoke but did not act. And we must not only abstain from evil deeds but even from the desire for them. Now He did not teach us these things as being opposed to the law, but as fulfilling the law and instilling in us the varied righteousness of the law. It would have been contrary to the law if He had commanded His disciples to do anything the law prohibited. But what He did command—namely, not only t
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Irenaeus, Against Heresies: Book IV Supporting witness
He says: “Swear not at all; neither by heaven, for it is God’s throne;
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Origen, De Principiis (On First Principles) Supporting witness
And again, But I say unto you, Swear not at all.
Did early Christians especially warn against false swearing?
Yes. Many early texts warn against false swearing, perjury, and careless oaths. Clement, Theophilus, the Apostolic Constitutions, Cyprian, and Lactantius all treat false swearing as sinful and dangerous, and the Bible passages in Sirach and the Prophets echo the same warning.
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Clement of Alexandria, The Stromata (Miscellanies) Direct teaching
The Gnostic speaks truthfully under oath, but he is not inclined to swear, and he rarely uses an oath, as we have said. When he speaks truth under oath, it comes from his agreement with the truth. So, speaking truth under oath is found to be the result of being correct in one's duties. Then where is the need for an oath for someone who lives according to the highest truth? So, the person who does not even swear will be far from committing perjury. And the one who does not break what has been confirmed by agreements will never swear, since the confirmation of both breaking and fulfilling agreements is shown by actions. Certainly, lying and perjury in making statements and swearing are contrary to duty. But the one who lives justly and does not fail in any of his duties, when the judgment of truth is closely examined, swears truth by his actions. Therefore, testimony by the tongue is unnecessary in his case.
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Theophilus of Antioch, To Autolycus Direct teaching
...ht us to keep away from unlawful idolatry, adultery, murder, sexual immorality, theft, greed, false swearing, anger, and every kind of lack of self-control and uncleanness. They taught that whatever a man would not want done to himself, he should not do to another. In this way, the one who lives righteously will escape eternal punishments and be considered worthy of the eternal life that comes from God.
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Apostolic Constitutions, Apostolic Constitutions Supporting witness
...ur being. Love your neighbor as yourself. Share the necessities of life with the needy. Avoid false swearing, and swearing often, and swearing in vain; for you shall not be held guiltless. Do not appear before the priests empty-handed, and continually offer your freewill offerings. Moreover, do not stay away from the church of Christ, but go there in the morning before all your work, and meet there again in the evening, to give thanks to God that He has preserved your life. Be diligent, steady, and hard-working in your calling. Offer your freewill offerings to the Lord, for He says, "Honor the Lord with the fruit of your honest labors," Proverbs 3:9. If you are not able to put anything considerable into the Corban, then at least give to strangers one, or two, or five mites. Store up for yourself heavenly treasure, which neither moth nor thieves can destroy, Matthew 6:20. And when you do this, do not judge your bishop, or any of your neighbors among the laity. For if you judge your brother, you become a judge without being appointed as one by anybody, for only the priests are entrusted with the power of judging. For to them it is said, "Judge righteous judgment," and again, "Appr
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Cyprian, Treatises Direct teaching
...es in marriage with unbelievers. They prostituted the members of Christ to the Gentiles. They would swear not only rashly, but even worse, falsely. They despised those set over them with proud arrogance. They spoke evil of one another with poisoned tongues. They fought with one another in stubborn hatred. Not a few bishops, who ought to have provided both exhortation and example to others, despised their divine office and became agents in worldly business. They left their seat, abandoned their people, wandered through foreign provinces, and searched the markets for profitable trade, while brothers were starving in the Church. They sought to possess money in hoards. They seized estates by crafty deceit. They increased their profits by multiplying usury. What do people like us not deserve to suffer for sins of this kind, when the divine rebuke has already warned us and said, "If they forsake my law and do not walk in my judgments, if they profane my statutes and do not keep my commandments, I will visit their offenses with a rod, and their sins with scourges"?
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Lactantius, The Epitome of the Divine Institutes Supporting witness
Let virtue alone please us. Its reward is immortal when it has conquered pleasure. But when the passions have been overcome and pleasures have been brought under control, the work of restraining other things is easy for the one who follows God and truth. He will never insult anyone, because he hopes for a blessing from God. He will not swear falsely, so that he may not mock God. In fact, he will not even swear at all, so that at some time, either from necessity or from habit, he may not fall into false swearing. He will say nothing deceitful and nothing with pretense. He will not refuse what he has promised, and he will not promise what he is unable to do. He will envy no one, since he is content with himself and with what he has. Nor will he take anything from another person, or wish harm to that person, on whom perhaps the gifts of God have been poured out more abundantly. He will not steal, and he will not desire anything that belongs to another. He will not lend his money at interest, because that is to seek profit from the troubles of others. However, he also will not refuse to lend if someone's need forces that person to borrow. He must not be harsh toward a son or toward a s
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Wisdom of Sirach 23:11 Background
A man that useth much swearing shall be filled with iniquity, And the plague shall never depart from his house: If he shall offend, his sin shall be upon him: And if he acknowledge not his sin, he maketh a double offense: And if he swear in vain, he shall not be innocent, But his house shall be full of calamities.
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Wisdom of Sirach 23:13 Background
Use not thy mouth to intemperate swearing, For therein is the word of sin.
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Wisdom of Sirach 23:9 Background
Accustom not thy mouth to swearing; Neither use thyself to the naming of the Holy One.
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Hosea 10:4 Background
They have spoken words, swearing falsely in making a covenant: thus judgment springeth up as hemlock in the furrows of the field.
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Wisdom of Solomon 14:30 Background
Howbeit for both causes shall they be justly punished: Both because they thought not well of God, giving heed unto idols, And also unjustly swore in deceit, despising holiness.
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Leviticus 19:12 Background
And ye shall not swear by my name falsely, neither shalt thou profane the name of thy God: I am the LORD.
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Wisdom of Solomon 14:28 Background
For either they are mad when they be merry, or prophesy lies, Or live unjustly, or else lightly forswear themselves.
Common Questions
Did the early church teach that Christians should never swear oaths?
Most early Christian writers said believers should not swear oaths in ordinary speech. A few texts discuss limited exceptions, but the main teaching is to speak truth plainly.
Which early Christian writers talk about oaths?
Justin Martyr, Irenaeus, Clement of Alexandria, Tertullian, Origen, Lactantius, the Didache, and the Apostolic Constitutions all speak against careless swearing.
What Bible verse did early Christians use most?
Matthew 5:34, along with James 5:12, was one of the main passages used to teach that Christians should not swear.
Source Index for Swearing Oaths
The guided sections above show the strongest quotations. This compact index highlights 154 ranked source links from 187 compiled sources for deeper study.
Source index 154 ranked links shown
Early Christian Writings 80 shown of 113
Primary-source quotations from early Christian writers and church documents.
Bible Passages 74 included
Related Bible passages saved for comparison with the early Christian quotations.