Sources for: What did early Christians believe about oaths?
This page gathers the early Christian writings first, followed by Bible passages and scripture references, and related resource links.
Sources Included
6 sources included Early Christian writings first · Bible passages second
Early Christian Writings 4 included
These are the early Christian writings and library sources behind the page.
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Jesus Forbids Oaths - What the Early Christians Said about Jesus Forbidding Oaths -Matthew 5:33-37
CYPRIAN: Is sincerity and truth maintained, when what is sincere is contaminated by unfaithful modifications, and what is true is morphed into a lie by deceptive cosmetics? Your Lord commands, "You cannot turn one hair white or black;" and you, in an attempt to resist your Lord's command, prove to be more powerful than Him, and tarnish your hair with audacious venture and impenitent disrespect. With ominous anticipation of the future, you kickstart your own introduction to red-haired demeanor; and sin (oh, the wickedness!) with your head—i.e., with the most distinguished part of your body! Even though it is recorded of the Lord, "His head and his hair were white like wool or snow," you revile that whiteness and detest that grayness which resembles the Lord's head. Treatise 2: On the Dress of Virgins, chapter 16 (Ante-Nicene Fathers 5.434) 5:37. APOLLONIUS THE APOLOGIST: During my defense speech, I request you, Perennis, to have faith that the pure and sacred teachings we have, we acquired from the Word of God, who is aware of all human thoughts. Additionally, he has directed us never to swear but to always speak the truth in all matters. It is already deemed a significant oath when truth is confirmed with a simple "yes"; hence it is unacceptable for a Christian to swear; for dishonesty breeds suspicion, and from suspicion comes the oath. Do you wish for me to swear that we res...
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Commentary on Matthew - Book X
…day, and said that the worthless man who loves things connected with birth keeps birthday feasts. Taking this suggestion from him, we find nowhere in Scripture that a righteous man kept a birthday. For Herod was more unjust than that famous Pharaoh. For on the latter man’s birthday feast, a chief baker is killed, Genesis 40:20. But by the former, John is killed, he than whom no one greater has risen among those born of women, Matthew 11:11, and about whom the Savior says, “But for what purpose did you go out? To see a prophet? Yes, I say to you, and more than a prophet.” Luke 7:26 But thanks be to God that, even if the grace of prophecy was taken from the people, a grace greater than all that was poured out among the Gentiles through our Savior Jesus Christ, who became free among the dead. For though He was crucified through weakness, yet He lives through the power of God. 2 Corinthians 13:4 Consider also the passage in which clean and unclean foods are discussed. Prophecy is despised when it is brought in on a platter instead of food. But the Jews do not have the head of prophecy, since they reject the crown of all prophecy, Christ Jesus. And the prophet is beheaded because of an oath, in a case where it was better to break the oath than to keep it. For the guilt of rashly taking an oath, and then breaking it because it was rash, is not equal to the guilt of a prophet’s deat...
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Who Were the Early Christians - Who Were the Early Christians
My name is Methodius. I am known as Methodius of Olympus because I served the church as bishop and teacher. I was born AD 270 and wrote against teachings that denied human responsibility and holiness. I believed obedience mattered because Christ had truly come in the flesh. When persecution returned, I did not flee. I was killed for my confession. I met the Lord around AD 311, having sealed my teaching with blood. My name is Theophilus. I am known as Theophilus of Antioch because I served as bishop there, in a city shaped by the apostles. I was born AD 170 and came to Christ from pagan learning. I lived where the Scriptures were read aloud and weighed carefully, and where the memory of Paul and Barnabas had not yet faded. I wrote Apology to Autolycus to defend the faith to a pagan friend, answering mockery with patience. I was the first to use the word "Trinity" to speak clearly of the Father, the Son, and the Holy Spirit—not to innovate, but to guard what the church already confessed. I met the Lord around AD 184, having labored to give the faith words that could protect it. My name is Aristides. I am known as Aristides of Athens because I defended the Christian faith before the emperor. I was born AD 100, trained as a philosopher, and converted to Christ while the apostolic writings were still shaping the churches. I wrote an apology addressed to Emperor Hadrian, explaining...
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Christ Fulfilled the Law - Early Christian Commentary on Christ Fulfilling the Law - Matthew 5:17-20
THE APOSTOLIC CONSTITUTIONS: Our Lord and Teacher, Jesus Christ, the Son of God, started by acting and then teaching, as Luke has mentioned somewhere: "which Jesus started to act and to teach." Therefore, he says: "Whoever shall act and teach, will be known as great in the kingdom of God." Book 2, Section 2, Chapter 6 (Ante-Nicene Fathers7.398). 5:20 JUSTIN MARTYR: For He urged His disciples to exceed the pharisaic way of life, cautioning them that if they did not, they could be certain they couldn't be saved; and these words are noted in the memoirs: "Unless your righteousness exceeds that of the Scribes and Pharisees, you will not enter into the kingdom of heaven." Dialogue With Trypho, A Jew, Chapter 105 (Ante-Nicene Fathers 1.252).
Related Resources 2 included
These are related pages, lessons, and media linked from the source review.
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Why is Your Commentary Different Than Other Commentaries?
What did they believe in the beginning? And to do that, it meant the last three years I've been putting into research on this, rereading the ante-Nicene Fathers, rereading Josephus, Philo, primary sources like that so that the commentary will reflect real information and will reflect what Christians believed in the beginning. So really, I think what it sounds like is maybe your goal with this commentary isn't so much what David thinks it's saying, but trying to take already known historical information from the early church and their writings about this book, the Gospel of Matthew, and bringing those together as a commentary from their perspective, almost, to an extent, versus necessarily just from your perspective.
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We Can Know The Truth - Brothers On A Journey - Intro Part 2 - Jason Willis
Well, what about that first church? What about the apostolic fathers? What about those men who were there to receive direct teaching and revelation from the apostles themselves, studied under them for decades? I wonder if they left any records at all of what the apostles actually meant in these scriptures. It turns out the anti-Nicene fathers did have a little bit of something to say, and it's all right here. Follow me here. This is so important. This Bible is scripture. This is not scripture. This Bible is 100% inspired by the Holy Spirit. This is not. This Bible is direct revelation from God. This is commentary about how the early church, the historic church, understood the revelation of this Bible.
Related Resources
Course Lesson
Why is Your Commentary Different Than Other Commentaries?
What did they believe in the beginning? And to do that, it meant the last three years I've been putting into research on this, rereading the ant...
Video
We Can Know The Truth - Brothers On A Journey - Intro Part 2 - Jason Willis
Well, what about that first church? What about the apostolic fathers? What about those men who were there to receive direct teaching and revelat...
Library Text
Matthew 5:33–37, where Jesus says not to swear at all
Read the early Christian or ANF source in context.
Library Text
Irenaeus states the point plainly
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Library Text
Tatian repeats Jesus’ words in the same literal form
Read the early Christian or ANF source in context.
Library Text
Tertullian is even more compressed
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Library Text
Origen likewise treats the command as literal
Read the early Christian or ANF source in context.
Library Text
Clement of Alexandria explains why a Christian should not need an oath
Read the early Christian or ANF source in context.
Library Text
Lactantius connects the same teaching to the command against false witness
Read the early Christian or ANF source in context.
Library Text
Jesus Forbids Oaths - What the Early Christians Said about Jesus Forbidding Oaths -Matthew 5:33-37
CYPRIAN: Is sincerity and truth maintained, when what is sincere is contaminated by unfaithful modifications, and what is true is morphed into a...
Answer Preview
Early Christians generally understood Jesus’ command, “Do not swear at all,” as a literal command: Christians should not take oaths, but should speak the truth so consistently that a simple yes or no is enough. They connected oath-refusal with a wider life of truthfulness, rejecting false swearing, lying, flattery, and deceit.
The Short Answer
The earliest Christian witness treated oaths as more than a speech habit. Jesus had moved beyond the older rule against false swearing and commanded His disciples not to swear at all, but to let their “yes” and “no” be truthful. That is the center of the Ante-Nicene answer to the question: Christians were to be people whose ordinary words could be trusted without an oath.
What Jesus Commanded
The decisive passage is Matthew 5:33–37, where Jesus says not to swear at all. He contrasts the older command, “Thou shalt not forswear thyself,” with His own command: “Swear not at all.” He then names common oath formulas—by heaven, earth, Jerusalem, or one’s own head—and rejects them. The reason is not merely that some oaths are careless. Heaven is God’s throne, earth His footstool, Jerusalem the city of the great King, and a person cannot make even one hair white or black.
The answer Jesus gives is simple: “Let your communication be, Yea, yea; Nay, nay.” Anything beyond this “cometh of evil.” Early Christians did not read that as a clever way to make better oaths. They read it as a command to stop using oaths and to become truthful people.
How Early Christians Understood It
Irenaeus states the point plainly: Jesus commanded Christians not only to avoid swearing falsely, but “not even to swear at all.” That distinction matters. The issue was not simply perjury. The Christian disciple was not to protect honesty by adding an oath; he was to speak truth without one.
Tatian repeats Jesus’ words in the same literal form: “Do not swear at all,” not by heaven, earth, Jerusalem, or one’s head. The approved Christian speech is “yes” or “no.” This is not presented as advice for unusually spiritual Christians, but as obedience to the Lord’s command.
Tertullian is even more compressed: “I will not speak about false swearing, because even swearing is not lawful.” He also says, “Christ commands that there must be no swearing.” His wording shows the same early Christian logic: if Christ forbids swearing, then the Christian does not need a separate discussion of which false oaths are forbidden. Swearing itself is the thing being refused.
Origen likewise treats the command as literal. He says many Gospel commands should be obeyed literally, and gives as an example the Lord’s words, “Do not swear at all.” He also says that when an oath is required, Christians should remember the One who taught, “Swear not at all.” Cyprian’s language is similar: being forced to swear an oath is described as being forced into something “not lawful.”
Oath-Refusal and Truthful Speech
The early Christian concern was not bare rule-keeping. Oath-refusal belonged to a larger discipline of truthful speech.
Clement of Alexandria explains why a Christian should not need an oath. A person with “well-established piety” refrains from lying and swearing. Clement defines swearing as “a firm affirmation, invoking the name of God,” then asks why a trustworthy person would need such a thing. His life should already testify to his truthfulness. Instead of swearing, he uses a simple yes or no; his conduct backs up his words.
Clement’s point is searching. A Christian’s life should be so steady and honest that the demand for an oath feels unnecessary. The answer to suspicion is not a louder formula, but a truthful life before God and neighbor.
Lactantius connects the same teaching to the command against false witness. He says the command has a wider meaning: because a lie deceives or harms, the just person must never speak falsely. He extends this to empty talk and flattery, because flattery is also harmful and deceitful. The Christian “will guard the truth everywhere.”
That phrase captures the heart of the matter. Early Christians did not treat oaths as an isolated topic. They believed Jesus was forming people who guarded truth in every setting: public speech, private promises, neighborly dealings, and moments of pressure.
Important Clarifications
The early witness distinguishes between the older command not to break oaths and Jesus’ command not to swear at all. The older law condemned false swearing and required vows to be kept. Jesus’ command goes further: the disciple’s speech should be truthful without invoking heaven, earth, Jerusalem, one’s head, or God’s name.
Clement’s discussion also shows that the goal is not evasive speech. Refusing oaths does not permit half-truths, manipulation, or technical honesty. The Christian who will not swear must be more truthful, not less. His yes should mean yes. His no should mean no.
Keep Studying
For the central Gospel text, study Jesus’ words on oaths in Matthew 5:33–37. For the Ante-Nicene interpretation, compare Irenaeus on not swearing at all, Tatian and Clement on yes-or-no speech, Tertullian and Origen on the literal command, Origen and Cyprian on being required to swear, and Lactantius on guarding truth everywhere.