Early Christian Views of Natural Law
Early Christians often said God put moral law in the human heart, so people can know right and wrong by conscience and reason. Irenaeus, Clement of Alexandria, Origen, Archelaus, Methodius, and Lactantius use that idea in different ways. They also connect it to Bible passages like Romans 2:14-15 and Jeremiah 31:33. The teaching is strongest on conscience and basic morality, and thinner when writers apply it to specific food laws or other disputed rules.
111 early-church witnesses · 211 source quotations · compared with Scripture
What did early Christians believe about natural Law?
Early Christian writers often tied natural law to God’s law written into the human heart, so people can know basic moral truth even before hearing Scripture. Irenaeus, Clement of Alexandria, Origen, Archelaus, Methodius, and Lactantius all connect natural law with conscience, reason, and the inner law that calls people to good. They also say Christ did not cancel that moral law but fulfilled and deepened it.
The evidence is broad and strong on basic moral order, conscience, and reason, but thinner and mixed when authors move from moral law to specific rules about food, marriage, or other cases. Many more early Christian quotations, Bible passages, and source links are gathered below so you can study the evidence for yourself.
Key Takeaways
- Early Christian writers often said natural law is God’s moral law written on the heart.
- Romans 2:14-15 was a key Bible passage for this idea.
- Irenaeus, Clement, Origen, Archelaus, Methodius, and Lactantius all speak about conscience, reason, or law in nature.
- Some writers applied natural law to specific topics like chastity or food laws, but those uses are secondary.
Questions Answered by the Sources
Did early Christians teach that natural law is written on the heart?
Several early writers say the law was implanted in human hearts or written on the inner person, and Bible passages are used to support that reading. The strongest witnesses here connect natural law with conscience, the inner man, and obedience to God.
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Irenaeus, Against Heresies: Book IV Direct teaching
1. And that the Lord did not abrogate the natural [precepts] of the law, by which man is justified, which also those who were justified by faith, and who pleased God, did observe previous to the giving of the law, but that He extended and fulfilled them, is shown from His words.
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Irenaeus, Against Heresies: Book IV Supporting witness
Because “the law was not established for righteous men.” But the righteous fathers had the meaning of the Decalogue written in their hearts and souls, that is, they loved the God who made them, and did no injury to their neighbour.
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Clement of Alexandria, The Stromata (Miscellanies) Supporting witness
Whether, then, it be the law which is connate and natural, or that given afterwards, which is meant, it is certainly of God;
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Peter of Alexandria, The Genuine Acts of Peter Supporting witness
the other from the law, which is in accordance with the commandment, which we had implanted in us as a natural law, stirring up our thoughts to good, when we delight in the law of God according to our mind, for this is the inner man;
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Methodius, From the Discourse on the Resurrection Supporting witness
the other from the law, which is in accordance with the commandment, which we had implanted in us as a natural law, stirring up our thoughts to good, when we delight in the law of God according to our mind, for this is the inner man;
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Archelaus, Disputation with Manes Supporting witness
and was pleased to give through Moses a written law to men, since verily the equity of the natural law filled to be retained in all its perfection in their hearts.
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Archelaus, Disputation with Manes Supporting witness
Well, then, I say that since, as wehave explained above, the law which was written naturally on men's hearts did not keep carefully by the memory of evil things, and since there was not a sufficiently established tradition among the elders, inasmuch as hostile oblivion always attached itself to the memory, and one man was instructed in the knowledge of that law by master, and another by himself, it easily came about that transgressions of the law engraved by nature did take place, and that through the violation of the commandments death obtained its kingship among men.
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Archelaus, Disputation with Manes Supporting witness
For when a man who has not the law does naturally the things contained in the law, he, not having the law, is a law unto himself.
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Methodius, From the Discourse on the Resurrection Supporting witness
...g condemned the sin that is in the body to its destruction, so that the righteousness of the law of nature, which draws us to good and agrees with the commandment, might be kindled and shown. For what the law of nature could not do, because it was weak and was overcome by the lust lying in the body, God gave power to accomplish by sending His own Son in the likeness of sinful flesh. Thus sin was condemned to its destruction, so that it would never again bear fruit in the flesh, and so that the righteousness of the law of nature might be fulfilled, overflowing in the obedience of those who walk not according to the lust of the flesh, but according to the desire and guidance of the Spirit. For the law of the Spirit of life, which is the Gospel, differs from the earlier laws. By its preaching it leads to obedience and the remission of sins, and it delivered us from the law of sin and death, having completely conquered sin that ruled over our flesh.
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Peter of Alexandria, The Genuine Acts of Peter Supporting witness
For the apostle here clearly sets out, as I think, three laws. One agrees with the good planted in us, and he plainly calls this the law of the mind. Another is the law that comes from the attack of evil, and it often pulls the soul toward lustful thoughts. This, he says, wars against the law of the mind, Romans 7:23. And the third agrees with sin, which is settled in the flesh through lust. He calls this the law of sin that dwells in our members, Romans 7:23. The Evil One urges this on and often stirs it up against us, driving us to unrighteousness and evil deeds. For there seems to be in us one thing that is better and another that is worse. When what is better by nature is about to become stronger than what is worse, the whole mind is carried toward what is good. But when what is worse grows and outweighs it, a man is driven instead toward evil thoughts. Because of this, the apostle prays to be delivered from it, regarding it as death and destruction. The prophet does the same when he says, "Cleanse me from my secret faults." The same meaning is shown by the words, "For I delight in the law of God after the inward man; but I see another law in my members, warring against the law
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Hermas, The Shepherd (Pastor) Supporting witness
... said. "This great tree, which casts its shadow over plains and mountains and all the earth, is the law of God that was given to the whole world. And this law is the Son of God, proclaimed to the ends of the earth. And the people under its shadow are those who have heard the proclamation and have believed in Him. And the great and glorious angel Michael is the one who has authority over this people and governs them. For he is the one who put the law into the hearts of believers. So he watches over those to whom he gave it, to see whether they have kept it. And you see each person's branches, because the branches are the law. So you see many branches that have become useless, and you will know all those who have not kept the law. And you will see where each one lives." I said to him, "Sir, why did he send some into the tower and leave others to you?" He answered, "All who broke the law that they received from him, he left under my authority for repentance. But all who fulfilled the law and kept it, he keeps under his own authority." "Who, then," I continued, "are those who were crowned and who go to the tower?" "These are the ones who have suffered because of the law. But the oth
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Origen, De Principiis (On First Principles) Supporting witness
Let us also look at the statement in Ezekiel, which says, “I will take away their stony hearts, and will put in them hearts of flesh, that they may walk in My statutes and keep My precepts.” For if God, when He wills, takes away stony hearts and implants hearts of flesh, so that His precepts are obeyed and His commandments are kept, it is not in our power to put away wickedness. For the taking away of the stony hearts is nothing else than the taking away of the wickedness by which a person is hardened, from the one from whom God wills to take it. And the implanting of a heart of flesh, so that a man may walk in the precepts of God and keep His commandments, what else is it than to become somewhat yielding and unresisting to the truth, and to be capable of practicing virtues? And if God promises to do this, and if, before He takes away the stony hearts, we do not lay them aside, it is clear that it does not depend on us to put away wickedness. And if it is not we who do anything toward the production within us of the heart of flesh, but if it is God’s doing, it will not be our own act to live agreeably to virtue, but altogether the result of divine grace. Such, then, will be the sta
More related quotations from this section 6 shown
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Methodius, From the Discourse on the Resurrection Supporting witness
...t us see, then, what we have tried to say about the apostle. When he says, "I was alive without the law once," Romans 7:9, he means the life lived in paradise before the law by our first parents. It was not a life without a body, but a life with a body, as we showed above. For we lived without lust, being completely unaware of its attacks. For when a person has no law by which he ought to live, and no authority establishing what kind of life he ought to choose, so that he may rightly be approved or blamed, he is considered free from accusation. Because a person cannot lust after things from which he is not restrained, and even if he did lust after them, he would not be blamed. For lust is not directed toward things that are before us and under our power, but toward things that are before us and not in our power. For how should anyone care about something that is neither forbidden to him nor necessary for him? For this reason it says, "I had not known lust, except the law had said, You shall not covet," Romans 7:7. For when our first parents heard, "Of the tree of the knowledge of good and evil, you shall not eat of it; for in the day you eat of it you shall surely die," Genesis
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Romans 2:15 Background
who show the work of the law written in their hearts, their conscience also bearing witness, and between themselves their thoughts accusing or else excusing them)
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Hebrews 8:10 Background
For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my laws into their minds, and write them on their hearts, and I will be their God, and they shall be my people.
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Jeremiah 31:33 Background
But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people.
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2 Corinthians 3:3 Background
clearly you are an epistle of Christ, ministered by us, written not with ink but by the Spirit of the living God, not on tablets of stone but on tablets of flesh, that is, of the heart.
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Romans 2:14 Background
For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law.
Did early Christians say Christ fulfilled or confirmed natural law?
Irenaeus, Victorinus, Novatian, and the Apostolic Constitutions say the Lord did not abolish the natural principles of the law but fulfilled, extended, or confirmed them. These sources present natural law as part of God’s moral order rather than something discarded by Christ.
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Lactantius, The Divine Institutes Direct teaching
...acter, and even among the same people they often changed with the times. But, he said, there was no natural law. All living creatures, both men and animals, are led by nature toward their own advantage. Therefore, there is no justice; or if there is any, it is the greatest foolishness, because it harms itself by promoting the interests of others. He brought forward these arguments. All nations that became great through power, even the Romans themselves, who were masters of the whole world, if they wished to be just, that is, to give back what belonged to others, would have to return to cottages and live in poverty and misery. Then, leaving general arguments, he came to particular cases. If a good man, he says, has a runaway slave, or an unhealthy and infected house, and he alone knows these faults, and for that reason offers it for sale, will he announce that the slave is a runaway and that the house he is offering for sale is infected, or will he hide it from the buyer? If he announces it, he is certainly good, because he does not deceive; but he will still be considered foolish, because he will either sell it for a low price or not sell it at all. If he hides it, he will certa
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Lactantius, The Divine Institutes Supporting witness
The substance of his disputation was this: That men enacted laws for themselves, with a view to their own advantage, differing indeed according to their characters, and in the case of the same persons often changed according to the times: but that there was no natural law: that all, both men and other animals, were borne by the guidance of nature to their own advantage;
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Athenagoras, The Resurrection of the Dead Supporting witness
...ing outside the matter, nor from what certain people think or have thought, but from the common and natural understanding of the matter itself, or from the connection of secondary truths with primary ones. For the question concerns either primary beliefs, and then all that is needed is remembrance, so that the natural understanding may be stirred up; or it concerns things that naturally follow from the first truths and their natural order. In these matters we must keep to the proper order. We must show what directly follows from the first truths, or from those things placed first, so that we neither lose sight of the truth, or of our certainty about it, nor confuse things that are arranged by nature and distinguished from one another, or break up the natural order. Therefore, I think it is fitting for those who want to treat this subject fairly, and who want to make an intelligent judgment about whether there is a resurrection or not, first to consider carefully the force of the arguments that help prove it, and what place each one holds — which is first, which second, which third, and which last. In arranging these, they should place first the cause of the creation of human bei
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Origen, De Principiis (On First Principles) Supporting witness
3. But since a rational animal not only has within itself these natural movements, but has moreover, to a greater extent than other animals, the power of reason, by which it can judge and determine regarding natural movements, and disapprove and reject some, while approving and adopting others, so by the judgment of this reason may the movements of men be governed and directed towards a commendable life.
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Origen, Against Celsus Supporting witness
So then, there are generally two laws set before us. One is the law of nature, of which God would be the lawgiver. The other is the written law of cities. When the written law is not opposed to the law of God, it is right for citizens not to abandon it under the excuse of foreign customs. But when the law of nature, that is, the law of God, commands what is opposed to the written law, consider whether reason does not tell us to say a long farewell to the written code, and to the desire of its lawmakers, and to give ourselves to God the lawgiver, and to choose a life agreeable to His word, even if in doing so it is necessary to face dangers, countless labors, and even death and dishonor. For when there are some laws in harmony with the will of God which are opposed to others that are in force in cities, and when it is impossible to please God and those who administer laws of that kind at the same time, it would be absurd to despise those acts by which we may please the Creator of all things, and to choose those by which we shall become displeasing to God, though we may satisfy ungodly laws and those who love them. But since it is reasonable in other matters to prefer the law of natu
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Origen, Against Celsus Supporting witness
We Christians, then, who have come to the knowledge of the law which is by nature king of all things, and which is the same with the law of God, endeavour to regulate our lives by its prescriptions, having bidden a long farewell to those of an unholy kind.
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Origen, De Principiis (On First Principles) Supporting witness
And from this it follows that, since the nature of this reason which is in man has within itself the power of distinguishing between good and evil, and while distinguishing possesses the faculty of selecting what it has approved, it may justly be deemed worthy of praise in choosing what is good, and deserving of censure in following that which is base or wicked.
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Tertullian, On Idolatry Supporting witness
Here I call Nature and Conscience as my witnesses: Nature, because even if the tongue in dictating remains motionless and quiet, the hand can write nothing which the soul has not dictated;
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1 Corinthians 2:14 Background
The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned.
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2 Corinthians 1:12 Background
For our rejoicing is this, the testimony of our conscience, that in simplicity and godly sincerity, not with fleshly wisdom, but by the grace of God, we have had our conversation in the world, and more abundantly to you-ward.
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Romans 1:20 Background
For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse.
Did early Christians connect natural law with conscience and moral judgment?
The sources often pair natural law with conscience, moral discernment, and judgment for wrongdoing. Origen, Tertullian, Lactantius, and others describe nature, reason, or conscience as a real guide that can approve the good and condemn the evil.
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Irenaeus, Against Heresies: Book IV Direct teaching
And that the Lord did not abolish the natural principles of the law, by which man is justified—principles which those justified by faith and who pleased God observed before the law was given—but instead extended and fulfilled them, is shown by His words. "For," He said, "it has been said to the people of long ago, Do not commit adultery. But I tell you, that anyone who looks at a woman lustfully has already committed adultery with her in his heart." And again: "It has been said, You shall not kill. But I tell you, anyone who is angry with 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 S
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Irenaeus, Against Heresies: Book IV Supporting witness
For God at the first, indeed, warning them by means of natural precepts, which from the beginning He had implanted in mankind, that is, by means of the Decalogue (which, if any one does not observe, he has no salvation), did then demand nothing more of them.
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Irenaeus, Against Heresies: Book IV Supporting witness
But He has increased and widened those laws which are natural, and noble, and common to all, granting to men largely and without grudging, by means of adoption, to know God the Father, and to love Him with the whole heart, and to follow His word unswervingly, while they abstain not only from evil deeds, but even from the desire after them.
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Victorinus, On the Creation of the World Supporting witness
How far, then, must that law be received spiritually, since, as I have shown by the authority of the apostle, it is spiritual, so that the divine and sure meaning of the law may be carried out? First, we must believe that whatever was appointed by God is clean and made pure by the authority of His very creation. It must not be spoken against, or the reproach would fall back on its Author. Also, the law was given to the children of Israel for this reason: that they might profit from it and return to those virtuous habits which they had received from their fathers, but had corrupted in Egypt through their dealings with a barbarous people. Finally, those ten commandments on the tablets teach nothing new, but remind them of what had been erased, so that righteousness in them, which had been asleep, might come to life again, as if by the breath of the law, like a fire that had been smothered. But they could also benefit by understanding that the vices especially to be avoided in men were the very ones the law condemned even in beasts. For when an irrational animal is rejected for some reason, it is really that same thing that is condemned in the man, who is rational. And if something in
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Victorinus, On the Creation of the World Supporting witness
...ted. We must not go back to the special rules about foods. Those rules were appointed for a certain reason, but now gospel liberty has removed them, since their obligation has been dismissed. The apostle cries out: "The kingdom of God is not food and drink, but righteousness, and peace, and joy." Romans 14:17 Also elsewhere: "Foods for the belly, and the belly for foods; but God will destroy both it and them. Now the body is not for sexual immorality, but for the Lord; and the Lord for the body." 1 Corinthians 6:13 God is not worshipped by the belly or by foods, which the Lord says will perish and are cleared away by natural law into the sewer. For the one who worships the Lord by foods is really like someone who has his belly as his lord. The true and holy and pure food, I say, is true faith, an unstained conscience, and an innocent soul. Whoever is fed in this way also feeds on Christ. Such a guest at the feast belongs to God. These are the feasts that feed the angels. These are the tables that the martyrs prepare. From here comes that word of the law: "Man does not live by bread alone, but by every word that proceeds from the mouth of God." Deuteronomy 8:3 And from here also
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Novatian, On the Jewish Meats Supporting witness
...hed. We must not go back to the special rules about foods. Those rules were appointed for a certain reason, but gospel liberty has now taken them away, since they have been discharged. The apostle cries out: "The kingdom of God is not food and drink, but righteousness, peace, and joy." Romans 14:17 Also elsewhere: "Foods for the belly, and the belly for foods; but God will destroy both it and them. Now the body is not for fornication, but for the Lord; and the Lord for the body." 1 Corinthians 6:13 God is not worshipped by the belly or by foods, which the Lord says will perish and are removed by the natural process into the drain. For the one who worships the Lord by foods is really like a man who has his belly as his lord. The true, holy, and pure food, I say, is true faith, an unstained conscience, and an innocent soul. Whoever is fed in this way also feeds on Christ. Such a guest belongs to God. These are the feasts that feed the angels. These are the tables the martyrs prepare. From here comes that word of the law: "Man does not live by bread alone, but by every word that proceeds from the mouth of God." Deuteronomy 8:3 And so also that saying of Christ: "My food is to do th
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Apostolic Constitutions, Apostolic Constitutions Supporting witness
Now the law is the Decalogue, which the Lord proclaimed to them with an audible voice before the people made that calf which represented the Egyptian Apis. And the law is righteous, and therefore it is called law, because judgments are made from it according to the law of nature. The followers of Simon misuse this, thinking they will not be judged by it and so will escape punishment. This law is good and holy, and it places no compulsion in positive matters. For He says, "If you will make me an altar, you shall make it of earth." He does not say, "Make one," but, "If you will make." He does not impose necessity, but gives permission to their own free choice. For God does not need sacrifices, since by nature He is above all need. But He knew that in former times Abel, beloved by God, and Noah and Abraham, and those who came after them, offered sacrifice to God from a thankful mind, without being required, but moved only by themselves through the law of nature. So now He permitted it to the Hebrews, not commanding it, but allowing it if they wished. And if they offered from a right intention, He showed Himself pleased with their sacrifices. Therefore He says: If you desire to offer,
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Apostolic Constitutions, Apostolic Constitutions Supporting witness
And the law is righteous, and therefore is it called the law, because judgments are thence made according to the law of nature, which the followers of Simon abuse, supposing they shall not be judged thereby, and so shall escape punishment.
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Apostolic Constitutions, Apostolic Constitutions Supporting witness
XXIII. For He did not take away the law of nature, but confirmed it.
Common Questions
Did early Christians believe in natural law?
Yes. Many early Christian writers said God wrote moral truth on the heart and that conscience and reason can guide people toward good.
Which Bible passages were used for natural law?
Romans 2:14-15, Jeremiah 31:33, Hebrews 8:10, and 2 Corinthians 3:3 are the main passages in this set.
Did they think natural law was enough by itself?
No clear writer here says it is enough by itself. They usually connect it to God’s law and to the gospel.
Source Index for Natural Law
The guided sections above show the strongest quotations. This compact index highlights 160 ranked source links from 211 compiled sources for deeper study.
Source index 160 ranked links shown
Early Christian Writings 80 shown of 111
Primary-source quotations from early Christian writers and church documents.
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Unknown, Unknown Work
Bible Passages 80 shown of 100
Related Bible passages saved for comparison with the early Christian quotations.