Is lying a mortal or venial sin?

But if the end intended be not contrary to charity, neither will the lie, considered under this aspect, be a mortal sin, as in the case of a jocose lie, where some little pleasure is intended, or in an officious lie, where the good also of one's neighbor is intended. Accidentally a lie may be contrary to charity by reason of scandal or any other injury resulting therefrom: and thus again it will be a mortal sin, for instance if a man were not deterred through scandal from lying publicly.

Thomas Aquinas, Aquinas, Summa Theologica II-II.Q110.A4

Therefore jocose and officious lies are not mortal sins. I answer that, A mortal sin is, properly speaking, one that is contrary to charity whereby the soul lives in union with God, as stated above ( Q[24], A[12] ; Q[35], A[3] ). Now a lie may be contrary to charity in three ways: first, in itself; secondly, in respect of the evil intended; thirdly, accidentally. A lie may be in itself contrary to charity by reason of its false signification. For if this be about divine things, it is contrary to the charity of God, whose truth one hides or corrupts by such a lie; so that a lie of this kind is opposed not only to the virtue of charity, but also to the virtues of faith and religion: wherefore it is a most grievous and a mortal sin.

Thomas Aquinas, Aquinas, Summa Theologica II-II.Q110.A4

Some say that for the perfect every lie is a mortal sin. But this assertion is unreasonable. … Wherefore an officious or a jocose lie is not a mortal sin in perfect men, except perhaps accidentally on account of scandal.

Thomas Aquinas, Aquinas, Summa Theologica II-II.Q110.A4

I answer that, As stated above ( Q[110], A[4] ), a mortal sin is one that is contrary to charity. Accordingly boasting may be considered in two ways. First, in itself, as a lie, and thus it is sometimes a mortal, and sometimes a venial sin. It will be a mortal sin when a man boasts of that which is contrary to God's glory---thus it is said in the person of the king of Tyre ( Ezech. 28:2 ): "Thy heart is lifted up, and thou hast said: … Sometimes it is a venial sin, when, to wit, a man boasts of things that are against neither God nor his neighbor.

Thomas Aquinas, Aquinas, Summa Theologica II-II.Q112.A2

The second class, called “mendacia officiosa,” includes all falsehoods uttered for a good object. Such as those told the sick by their attendants, to comfort or encourage them; those told by detectives for the discovery of crimes; or those which are designed to prevent evil or secure good for ourselves or others. All such falsehoods are pronounced by Romanists to be venial sins, mere peccadilloes.

Charles Hodge, Hodge, Systematic Theology III.19.13 (Vol. 3)

Sarah lied, because she was ashamed of laughing: the serpent lied, tempting man to disobey and change to a divine existence. Falsehoods differ widely according to their motives.

Gregory of Nyssa, Gregory of Nyssa, Against Eunomius 3.10 (Nicene and Post-Nicene Fathers, Series 2, Vol. 5)

In fine, there are two kinds of lies, in which there is no great fault, and yet they are not without fault, either when we are in jest, or when we lie that we may do good.

Augustine of Hippo, Augustine, Expositions on the Book of Psalms 5 (Nicene and Post-Nicene Fathers, Series 1, Vol. 8)

In these eight kinds, however, a man sins less when he tells a lie, in proportion as he emerges to the eighth: more, in proportion as he di verges to the first. But whoso shall think there is any sort of lie that is not sin, will deceive himself foully, while he deems himself honest as a deceiver of other men.

Augustine of Hippo, Augustine, On Lying 42 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

For first to be eschewed is that capital lie and far to be fled from, which is done in doctrine of religion; to which lie a man ought by no consideration to be induced. … The fourth, that which is done through only lust of lying and deceiving, which is an unmixed lie. The fifth, what is done with desire of pleasing by agreeableness in talk. All these being utterly eschewed and rejected, there follows a sixth sort which at once hurts nobody and helps somebody; as when, if a person’s money is to be unjustly taken from him, one who knows where the money is, should say that he does not know, by whomsoever the question be put.

Augustine of Hippo, Augustine, On Lying 25 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

For, if a lie spoken against a man’s temporal life is detestable, how much more one against eternal life? as is every lie, if it take place in doctrine of religion. And it is for this reason that the Apostle calls it false witness, if a man tell a lie about Christ, yea, one which may seem to pertain to His praise. Now if it be a lie that neither inventeth or hideth any man’s sin, nor is an swered to a question of the judge, and hurteth no man, and profits some man, are we to say that it is neither false witness, nor a reprehensible lie?

Augustine of Hippo, Augustine, On Lying 21 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

But he who says that some lies are just, must be judged to say no other than that some sins are just, and therefore some things are just which are unjust: than which what can be more absurd? For whence is a thing a sin, but for that it is contrary to justice? Be it said then that some sins are great, some small, because it is true; and let us not listen to the Stoics who maintain all to be equal: but to say that some sins are unjust, some just, what else is it than to say that there be some unjust, some just iniquities?

Augustine of Hippo, Augustine, Against Lying 31 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

For although, as far as a man’s own conscience is concerned, it is a greater evil to deceive than to be deceived, nevertheless it is a far less evil to tell a lie in regard to matters that do not relate to religion, than to be led into error in regard to matters the knowledge and belief of which are essential to the right worship of God.

Augustine of Hippo, Augustine, The Enchiridion 18 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

Now it is evident that the greater the good intended, the more is the sin of lying diminished in gravity.

Thomas Aquinas, Aquinas, Summa Theologica II-II.Q110.A2

I answer that, As stated above ( Q[110], AA[2] ,4), one lie is more grievous than another, sometimes on account of the matter which it is about---thus a lie about a matter of religious doctrine is most grievous---and sometimes on account of the motive for sinning; thus a mischievous lie is more grievous than an officious or jocose lie.

Thomas Aquinas, Aquinas, Summa Theologica II-II.Q113.A2

Nor is it without reason written in another place, “The mouth that lieth slayeth the soul:” lest any should imagine that the perfect and spiritual man ought to lie for this temporal life, in the death of which no soul is slain, neither his own, nor another’s. But since it is one thing to lie, another to conceal the truth (if indeed it be one thing to say what is false, another not to say what is true), if haply one does not wish to give a man up even to this visible death, he should be prepared to conceal what is true, not to say what is false; so that he may neither give him up, nor yet lie, lest he slay his own soul for another’s body.

Augustine of Hippo, Augustine, Expositions on the Book of Psalms 5 (Nicene and Post-Nicene Fathers, Series 1, Vol. 8)

Make answer then to him who says, Lie, for it is written, “All men are liars:” I will not lie, for it is written, “The mouth that lieth slayeth the soul.” I will not lie, because it is written, “Thou shalt destroy them that speak lying.” I will not lie, because it is written, “Thou shalt not bear false witness.” Though he whom I displease by the truth harass my body with oppressions, I will give ear to my Lord, “Fear not them which kill the body.”

Augustine of Hippo, Augustine, Sermons on Selected Lessons of the New Testament 33 (Nicene and Post-Nicene Fathers, Series 1, Vol. 6)

You must either deny that you are a sinner if you are not to be in danger of Gehenna: or, if you are a sinner you will be sent to hell for even a light offence: “The mouth that lieth,” says one, “kills the soul.”

Jerome, Jerome, Against Jovinianus 2 (Nicene and Post-Nicene Fathers, Series 2, Vol. 6)

Truth is too valuable a thing to be sold for a jest, and so is the reputation of our neighbour. By lying and slandering in jest men learn themselves, and teach others, to lie and slander in earnest; and a false report, raised in mirth, may be spread in malice; besides, if a man may tell a lie to make himself merry, why not to make himself rich, and so truth quite perishes, and men teach their tongues to tell lies, Jer. ix. 5 . If men would consider that a lie comes from the devil, and brings to hell-fire, surely that would spoil the sport of it; it is casting arrows and death to themselves.

Matthew Henry, Henry, Commentary on Proverbs 26.14 (Commentary on the Whole Bible, Vol. 3)

For where is the harm of believing that such an one’s father or grandfather was a good man, when he was not? or that he has served with the army even in Persia, though he never set foot out of Rome? But to the persons who tell these lies, they do much harm: to the former sort, because they so desert truth as to rejoice in deceit: to the latter, because they want to please people better than the truth.

Augustine of Hippo, Augustine, On Lying 18 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

For faith hath its name in the Latin tongue, from that the thing is done which is said: and thus it is manifest that one doth not exhibit when telling a lie. And even if this faith be less violated, when one lies in such sort that he is believed to no inconvenience and no pernicious hurt, with added intention moreover of guarding either one’s life or corporal purity; yet violated it is, and a thing is violated which ought to be kept safe in chastity and sanctity of mind.

Augustine of Hippo, Augustine, On Lying 41 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

Of lies are many sorts, which indeed all, universally, we ought to hate. For there is no lie that is not contrary to truth. … Yet in truth there be some lies which to believe does no harm: although even by such sort of lie to wish to deceive, is hurtful to him that tells it, not to him that believes it.

Augustine of Hippo, Augustine, Against Lying 4 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

Either then we are to eschew lies by right doing, or to confess them by repenting: but not, while they unhappily abound in our living, to make them more by teaching also. But let him who thinks this, choose out whereby he may help his fellow man being in peril, to what safety he will, what kinds soever of lies; provided yet even of such men we obtain our demand, that upon no cause must we be carried on to false-swearing and to blaspheming. These wickednesses at least let us judge either greater than deeds of lewdness, or certainly not smaller.

Augustine of Hippo, Augustine, Against Lying 41 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

It will be almost as needless to expatiate on the Baseness and meanness of that sin; for though there is no Subject that affords more matter for Declamation, yet Lying is a thing that is ashamed of itself, and therefore may well be remitted to its own convictions. Tis Aristotle’s observation, that all Elements but the Earth, had some Philosopher or other, that gave it his vote to be the first productive Principle of all things: and I think we may now say, that all Crimes have had their Abettors and fautors, somebody that would stand up in their defense; only Lying is so much the dregs and refuse of wickedness, that none had yet had Chemistry enough to sublimate it, to bring it into such a reputation, that any man will think fit to own it: the greater wonder that what is under so universal a reproach, should be so commonly admitted in practice.

Richard Allestree, Allestree, The Government of the Tongue 9

Lying, in commerce or conversation, is a sin which every good man hates and abhors, hates and doubly hates, because of the seven things which the Lord hates one is a lying tongue and another is a false witness that speaks lies, Prov. vi. 16 . Every man hates to have a lie told him; but we should more hate telling a lie because by the former we only receive an affront from men, by the latter we give an affront to God.

Matthew Henry, Henry, Commentary on Psalms 119.116 (Commentary on the Whole Bible, Vol. 3)

To hate lying, and to keep at the utmost distance from it, because it is an abomination to the Lord, and renders those abominable in his sight that allow themselves in it, not only because it is a breach of his law, but because it is destructive to human society.

Matthew Henry, Henry, Commentary on Proverbs 12.22 (Commentary on the Whole Bible, Vol. 3)

Next to a proud look nothing is more an abomination to God than a lying tongue; nothing more sacred than truth, nor more necessary to conversation than speaking truth.

Matthew Henry, Henry, Commentary on Proverbs 6.3 (Commentary on the Whole Bible, Vol. 3)

It is the undoubted character of every righteous man that he hates lying (that is, all sin, for every sin is a lie, and particularly all fraud and falsehood in commerce and conversation), not only that he will not tell a lie, but he abhors lying, from a rooted reigning principle of love to truth and justice, and conformity to God. 2. Where sin reigns the man is loathsome. If his eyes were opened, and his conscience awakened, he would be so to himself, he would abhor himself and repent in dust and ashes; however, he is so to God and all good men; particularly, he makes himself so by lying, than which there is nothing more detestable.

Matthew Henry, Henry, Commentary on Proverbs 13.5 (Commentary on the Whole Bible, Vol. 3)

Of the sin of lying in particular; it is a fruitful sin, and upon this account exceedingly sinful: one lie needs another to support it, and that another. It is a rule in the devil's politics Male facta male factis tegere, ne perpluant — To cover sin with sin, in order to escape detection.

Matthew Henry, Henry, Commentary on John 18.2 (Commentary on the Whole Bible, Vol. 5)

Observe, Lying is a very great sin, a peculiar violation of the obligations which Christians are under, and very injurious and hurtful to Christian society.

Matthew Henry, Henry, Commentary on Ephesians 4.3 (Commentary on the Whole Bible, Vol. 6)

An indifference to the sin of lying, whether among old or young, rich or poor, is one of the most unmistakable symptoms of an ungodly condition.

J.C. Ryle, Ryle, Expository Thoughts on John John 8:37-47 (Expository Thoughts on the Gospels, Vol. 4)

Many lies indeed seem to be for some one’s safety or advantage, spoken not in malice, but in kindness: such was that of those midwives in Exodus, who gave a false report to Pharaoh, to the end that the infants of the children of Israel might not be slain. But even these are praised not for the fact, but for the disposition shown; since those who only lie in this way, will attain in time to a freedom from all lying.

Augustine of Hippo, Augustine, Expositions on the Book of Psalms 5 (Nicene and Post-Nicene Fathers, Series 1, Vol. 8)

But, like as it is asked of what mouth the Scripture saith, “The mouth that lieth, slayeth the soul,” so it may be asked, of what lie. For it seems to speak of that lie in particular, which consists in detraction. It says, “Keep yourselves from murmuring, which profiteth nothing, and from detraction refrain your tongue.” Now this detraction takes place through malevolence, when any man not only with mouth and voice of the body doth utter what he forgeth against any, but even without speaking wisheth him to be thought such; which is in truth to detract with the mouth of the heart; which thing, it saith, cannot be obscure and hidden from God.

Augustine of Hippo, Augustine, On Lying 33 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)

For in many things a relaxation by way of indulgence is allowed to infirmity, although in her utmost sincerity the things be nowise pleasing to truth. Let him say this, whoever dreads not the consequences which are to be dreaded, if once there shall be in any way any lies permitted. In nowise, however, must they be permitted to climb up to such a height as to reach to perjuries and blasphemies: nor must any plea whatever be held out, for which it should be right that perjury should be committed, or, what is more execrable, that God should be blasphemed.

Augustine of Hippo, Augustine, Against Lying 39 (Nicene and Post-Nicene Fathers, Series 1, Vol. 3)