Early Christian Teaching on Mortal Sin
Early Christian writers often spoke of some sins as deadly, grave, or beyond pardon, especially adultery, fornication, idolatry, apostasy, and willful sin after knowing the truth. Tertullian gives the strongest wording, and Clement, Cyprian, and Lactantius add close support. Bible passages like 1 John 5:16-17 and Hebrews 10:26 are the main texts behind the discussion. The evidence is strong for serious sin and weak on one fixed list for all churches.
119 early-church witnesses · 217 source quotations · compared with Scripture
What did early Christians believe about mortal sin?
Early Christian writers often treated some sins as deadly or grievous in a way that could not be casually brushed aside, especially adultery, fornication, idolatry, apostasy, and willful sin after knowing the truth. Tertullian is the clearest witness here, and Clement of Alexandria, Cyprian, and Lactantius also speak of sins that bring death or no further pardon. The Bible passages most often tied to this idea are 1 John 5:16-17, Hebrews 10:26, 2 Peter 2:20-21, and Mark 3:29.
The evidence is broad for the idea of serious, possibly irremissible sins, but mixed on exact lists, because some writers stress repentance while others stress no pardon for certain acts. The page is strongest when it focuses on mortality, death, and loss of forgiveness for grave post-baptism or willful sin. Many more early Christian quotations, Bible passages, and source links are gathered below so you can study the evidence for yourself.
Key Takeaways
- Tertullian called adultery and fornication mortal sins and said they were not to be lightly forgiven.
- Clement of Alexandria cited 1 John 5:16-17 to distinguish sins that lead to death from sins that do not.
- Cyprian and Lactantius spoke of some willful sins as having no pardon or no remission.
Questions Answered by the Sources
Did early Christians treat some sins as mortal or unto death?
Yes. The strongest sources explicitly distinguish a "sin unto death" from other sins, and some writers say certain grave sins are not to be requested for or are not granted remission in the same way as lesser sins.
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Tertullian, On Modesty Direct teaching
... mindful that Jeremiah had been prohibited by God to deprecate Him on behalf of a people committing mortal sins. Every unrighteousness is sin, and there is a sin unto death. But we know that everyone who has been born of God does not sin—to wit, the sin which is unto death. Thus there is no course left for you but either to deny that adultery and fornication are mortal sins, or else to confess them irremissible, for which it is not permitted even to make successful intercession.
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Cyprian, Epistles Supporting witness
sin no more, lest a worse thing happen unto you, John 5:14 let him separate the fraudulent and adulterers from his side and from his company, since the case of an adulterer is by far both graver and worse than that of one who has taken a certificate, because the latter has sinned by necessity, the former by free will: the latter, thinking that it is sufficient for him that he has not sacrificed, has been deceived by an error;
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Irenaeus, Against Heresies: Book V Supporting witness
but that after the Lord’s appearance, when he had clearly ascertained from the words of Christ and His apostles that eternal fire has been prepared for him as he apostatized from God of his own free-will, and likewise for all who unrepentant continue in the apostasy, he now blasphemes, by means of such men, the Lord who brings judgment [upon him] as being already condemned, and imputes the guilt of his apostasy to his Maker, not to his own voluntary disposition.
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Hippolytus, Refutation of All Heresies Supporting witness
This one propounded the opinion, that, if a bishop was guilty of any sin, if even a sin unto death,1 John 5:16 he ought not to be deposed.
Did early Christians think willful sin after knowing the truth was especially serious?
Several sources say that sin committed after receiving knowledge of the truth, or after believing, is treated as more serious than earlier ignorance. The Bible passages and early writers alike connect this with worse judgment, no more sacrifice for sins, or refusal to restore in the same way.
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Tertullian, On Modesty Supporting witness
without prejudice to that species of repentance after believing, which either, for lighter sins, will be able to obtain pardon from the bishop, or else, for greater and irremissible ones, from God only.
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Lactantius, The Divine Institutes Direct teaching
he who sins wilfully has no pardon. Nor, however, if any one shall have been purified from all stain of sin, let him think that he may abstain from the work of bounty because he has no faults to blot out.
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Cyprian, Treatises Supporting witness
Moses also pleaded for the sins of the people. Yet when he asked pardon for these sinners, he did not receive it. He said, "I pray You, O Lord, this people have committed a great sin, and have made for themselves gods of gold. Yet now, if You will forgive their sin, forgive it; but if not, blot me out of the book that You have written." And the Lord said to Moses, "Whoever has sinned against Me, I will blot out of My book." Exodus 32:31-33 He was the friend of God. He had often spoken face to face with the Lord. Yet he could not obtain what he asked, nor could he calm the wrath of an angry God by his plea. God praises Jeremiah and declares, saying, "Before I formed you in the womb, I knew you; and before you came out of the womb I sanctified you, and I ordained you a prophet to the nations." Jeremiah 1:5 And to the same man He says, when he often begged and prayed for the sins of the people, "Do not pray for this people, nor lift up a cry or prayer for them; for I will not hear them in the time when they call on Me, in the time of their affliction." Jeremiah 7:16 But who was more righteous than Noah, who, when the earth was filled with sins, alone was found righteous on the earth?
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Apostolic Constitutions, Apostolic Constitutions Direct teaching
Therefore, bishop, let your care reach every kind of person: those who have not sinned, so that they may remain innocent; and those who do sin, so that they may repent. For the Lord says this to you: "Take heed that you do not offend one of these little ones" in Matthew 18:10. It is also your duty to grant forgiveness to those who repent. For as soon as someone who has sinned says with sincere heart, "I have sinned against the Lord," the Holy Spirit answers, "The Lord also has forgiven your sin; be of good cheer, you shall not die." Therefore, bishop, understand the dignity of your office. As you have received the power of binding, so you have also received the power of loosing. Since you have the power of loosing, know yourself, and conduct yourself in this world in a way that fits your office, knowing that you must give a great account. For to those whom, as the Scripture says, men have entrusted much, they will require the more, in Luke 12:48. For no man is free from sin, except Him who was made man for us. For it is written, "No man is pure from filthiness, no, not even if his life is only one day long." For this reason, the lives and conduct of the ancient holy men and patriar
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Apostolic Constitutions, Apostolic Constitutions Supporting witness
But if any one sin in direct opposition, and on purpose to try whether God will punish the wicked or not, such a one shall have no remission, although he say with himself, All is well, and I will walk according to the conversation of my evil heart.
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Apostolic Constitutions, Apostolic Constitutions Supporting witness
XXIII. There is no sin more grievous than idolatry, for it is an impiety against God: and yet even this sin has been forgiven, upon sincere repentance.
More related quotations from this section 1 shown
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Tertullian, On Modesty Supporting witness
Every sin is dischargeable either by pardon or else by penalty: by pardon as the result of chastisement, by penalty as the result of condemnation.
Which sins did early Christians most often describe as deadly or irremissible?
Among the supplied sources, adultery, fornication, apostasy, idolatry, and deliberate rebellion appear most often in the stronger claims about grave sin. The texts do not present one universal list, but they repeatedly single out these kinds of acts as especially dangerous or unforgivable in context.
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1 John 5:16 Direct teaching
If anyone sees his brother committing a sin not leading to death, he shall ask, and God will give him life—to those who commit sins that do not lead to death. There is sin that leads to death; I do not say that one should pray for that.
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Hebrews 10:29 Direct teaching
Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
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Hebrews 10:26 Direct teaching
For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
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2 Peter 2:20 Supporting witness
For if, after they have escaped the pollutions of the world through the knowledge of the Lord and Savior Jesus Christ, they are again entangled in them and overcome, the latter end is worse for them than the beginning.
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2 Peter 2:21 Supporting witness
For it had been better for them not to have known the way of righteousness, than, after they have known it, to turn from the holy commandment delivered unto them.
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Mark 3:29 Supporting witness
But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation.
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1 John 5:17 Supporting witness
All wrongdoing is sin, but there is sin that does not lead to death.
More related quotations from this section 4 shown
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Clement of Alexandria, The Stromata (Miscellanies) Supporting witness
... You see the one God declared good, rendering according to desert, and forgiving sins. John, too, clearly teaches the differences of sins in his larger Epistle, in these words: "If any man see his brother sin a sin that is not unto death, he shall ask, and he shall give him life"—for those who sin not unto death, he says. "For there is a sin unto death: I do not say that one is to pray for it. All unrighteousness is sin; and there is a sin not unto death." 1 John 5:16-17
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Clement of Alexandria, The Stromata (Miscellanies) Supporting witness
For if we sin wilfully after that we have received the knowledge of the truth, there remains no more sacrifice for sins, but a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
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Clement of Alexandria, The Stromata (Miscellanies) Supporting witness
All unrighteousness is sin; and there is a sin not unto death. 1 John 5:16-17
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Clement of Alexandria, The Stromata (Miscellanies) Supporting witness
For there is a sin unto death: I do not say that one is to pray for it.
Common Questions
Did the early Christians believe some sins were worse than others?
Yes. Writers like Clement of Alexandria and Tertullian distinguished between sins that lead to death and sins that do not.
Did early Christians think mortal sin could be forgiven?
Some writers allowed repentance for certain grave sins, while others said some sins were irremissible or had no pardon.
What Bible verse did early Christians use for mortal sin?
The main verse was 1 John 5:16-17, along with Hebrews 10:26, 2 Peter 2:20-21, and Mark 3:29.
Source Index for Mortal sin
The guided sections above show the strongest quotations. This compact index highlights 160 ranked source links from 217 compiled sources for deeper study.
Source index 160 ranked links shown
Early Christian Writings 80 shown of 119
Primary-source quotations from early Christian writers and church documents.
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Justin Martyr, Other Fragments from the Lost Writings of Justin
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Justin Martyr, Other Fragments from the Lost Writings of Justin
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Clement of Rome, Connection to Romans 1:32
Bible Passages 80 shown of 98
Related Bible passages saved for comparison with the early Christian quotations.
Related Resources
Course Lesson
True Peace Beyond Mortal Judgment
Open a related course lesson for more teaching connected with Mortal sin.