What Does the Bible Say About Lying? The Catholic Answer

God forbids lying absolutely: "Thou shalt not bear false witness against thy neighbour" (Exodus xx. 16, the Eighth Commandment, Douay-Rheims). Yes, lying is a sin — always, by its very nature — because a lie sets the word against the mind, and God is Truth. Scripture is plain on what it costs: the devil himself "is a liar, and the father thereof" (St John viii. 44), and "lying lips are an abomination to the Lord" (Proverbs xii. 22).

What does the Bible say about lying?

The Bible does not treat lying as a small fault. Among the seven things God hates, Solomon names "a lying tongue" and "a deceitful witness that uttereth lies" (Proverbs vi. 16-19, Douay-Rheims), and "lying lips are an abomination to the Lord; but they that deal faithfully please him" (Proverbs xii. 22). The Apocalypse, listing those shut out of heaven, ends with "all liars," who "shall have their portion in the pool burning with fire and brimstone, which is the second death" (Apocalypse xxi. 8) — a sober answer to those who ask what God says about hell. The liar is set in the company of murderers and idolaters. (For the wider series, see what God says on the things that trouble conscience.)

Our Lord traces the lie to its source. To those who refused His word He said: "You are of your father the devil... He was a murderer from the beginning, and he stood not in the truth; because truth is not in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father thereof" (St John viii. 44). The first sin entered the world by a lie, when the serpent told Eve, "No, you shall not die the death" (Genesis iii. 4). To lie is to imitate the devil; to tell the truth is to imitate Christ, who is "the way, and the truth, and the life" (St John xiv. 6). These are among the plainest Catholic Bible verses on the matter, and they leave no room for an honest lie.

Is lying a sin?

Lying is always a sin. This is worth stating without softening, because it is one of the points where popular opinion most often goes astray: many grant that a malicious lie is wrong yet suppose that a small or kindly lie is no sin at all. The Catechism of St Pius X answers directly: "It is never lawful to lie, neither in jest, nor for one's own advantage, nor for that of another, for it is a thing evil in itself" (Catechism of St Pius X, Part III, ch. 3). A thing evil in itself cannot be made good by any intention, however kind. We may not do evil that good may come of it (Romans iii. 8).

St Thomas Aquinas gives the reason. Words are signs naturally ordered to express what is in the mind; a lie wills to signify what one knows to be false, and so it is "essentially and formally" a sin against truth (Summa Theologiae, II-II, q. 110, a. 3). Because the disorder lies in the very act and not merely in the harm done, no lie can be free of sin. The difference between mortal and venial sin turns on the matter and the harm, not on whether the act was a sin at all.

The three kinds of lie

The Catechism of St Pius X sets out three kinds, and we keep its order and names. The jocose lie is one told "in pure jest and without doing harm to anyone." The officious lie is the affirmation of a false thing for one's own advantage or another's, "but without there being any prejudice to anyone" — the so-called white lie, told to spare feelings or gain a small convenience. The pernicious lie is the affirmation of a false thing "which does wrong to one's neighbour" (Catechism of St Pius X, Part III, ch. 3).

The Catechism then weighs them: "When the lie is jocose or officious, it is a venial sin; but if it be pernicious, it is a mortal sin if the prejudice caused be grave" (St Pius X, III, 3). Mark the teaching exactly. The jocose and officious lie are not lawful; they are venial sins — real faults, to be confessed and amended, but not severed from grace. Only the pernicious lie that does grave harm is mortal: the lie that wrecks a man's good name, robs him of justice, or betrays a grave trust. The Roman Catechism warns why even the small lie is dangerous: "from the lie in jest to the grave lie, the slope is very steep" (Roman Catechism, Part III, ch. 36).

St Augustine: never lawful, even for a good end

The hardest case is the lie told to save a life or shield the innocent, and here the Church follows St Augustine without flinching. He wrote two treatises against lying precisely to refuse the comforting exception. The Roman Catechism cites him: "we must be useful to no one by a lie, still less by perjury" (Roman Catechism, Part III, ch. 36, citing St Augustine, Contra Mendacium). One may not commit even a small sin to prevent another's great one; the sin remains the sinner's own.

This is firm doctrine, and we will not blunt it: the end does not justify the means. The mother who would lie to a murderer at the door faces a true and bitter trial, and the Church does not pretend otherwise — but she does not therefore call the lie good. What she offers instead is the lawful path of silence, refusal, or careful speech, which is not a lie at all. The same refusal to do evil for a good end governs the Church's hard teaching on war, on revenge, and on the law of charity that forbids us to repay hate with sin.

Mental reservation distinguished

Here a true distinction must be drawn, for it is often confused with permission to lie. A lie asserts as true what one holds false (St Pius X, III, 3). A mental reservation is different: it speaks words true in themselves while withholding part of the truth, when the hearer has no right to the knowledge he seeks. The servant who answers "He is not at home" of a master who will not receive a caller, meaning not at home to you, has not asserted a falsehood; he has declined to surrender what the caller has no right to demand.

St Thomas grounds this: we are not always bound to utter the whole truth, but we are always bound never to assert the false (Summa Theologiae, II-II, q. 110). A man may keep silence or answer in words true in themselves though not understood as the questioner wishes; what he may never do is say what he knows to be untrue. The line must be kept exact, lest "mental reservation" become a cloak for ordinary lying. Where there is a duty to speak plainly — under lawful oath, to a confessor, to those whose office gives them the right — there is no room for reservation, and to mislead is to lie.

The duty of truthfulness

The Eighth Commandment does not only forbid; it commands. It "commands us to tell the truth when we must, and to interpret in a good sense, as far as we can, the actions of our neighbour" (Catechism of St Pius X, Part III, ch. 3). Truthfulness is owed to God, who is Truth, and to our neighbour, whom we wrong by deceit.

Beyond the lie itself, this commandment forbids detraction — making known another's hidden faults without just cause — calumny, which attributes faults he has not, flattery, rash judgment, and suspicion (St Pius X, III, 3). These sins of the tongue stand beside those the Second Commandment forbids, where the Church weighs swearing and cursing by the reverence owed to God's name. Against rash judgment it sets the positive duty of charity: to read our neighbour's deeds in the better sense, the same charity treated under judging others.

And the duty does not end at confession. For one who has sinned against this commandment, "it is not enough that he confess it; he is bound to retract what he has said in calumny against his neighbour, and to repair, as best he can, the damages he has caused him" (St Pius X, III, 3). As the thief must restore, the calumniator must retract: the reputation he stole must be given back. This duty binds the whole household, where parents teach children the love of truth by their own; it belongs to the order of the family as much as to the courtroom. Truthfulness is the fruit of the love of God, for "he that loveth not, knoweth not God" (1 St John iv. 8), and no man loves God who serves the father of lies.

The Eighth Commandment, then, is no small precept. It binds the tongue to the mind and both to God. This precept stands among the Ten Commandments that bind us all, and a lie serves pride, the chief of the seven deadly sins. Every one of us has sinned with the tongue, and the Church meets the liar not with despair but with a door. Examine your conscience by it before Confession — every lie, every detraction, every calumny, the truths owed and withheld — bring it to confession, retract what you have falsely said, and make whatever amends you can. To bind the tongue to the mind is simply to live in the truth, and "the truth shall make you free" (St John viii. 32).

Frequently Asked Questions

What does God say about lying?

God forbids lying absolutely in the Eighth Commandment: "Thou shalt not bear false witness against thy neighbour" (Exodus xx. 16, Douay-Rheims). Because God is Truth and a lie sets the word against the mind, "lying lips are an abomination to the Lord" (Proverbs xii. 22). Our Lord names the devil "a liar, and the father thereof" (St John viii. 44), so to lie is to imitate Satan rather than Christ.

What does God say about lying to your spouse?

A lie to one's husband or wife is still a lie, and the Catechism of St Pius X teaches that "it is never lawful to lie, neither in jest, nor for one's own advantage, nor for that of another" (Part III, ch. 3). Marriage binds the spouses in a special bond of charity and trust, so deceit within it wounds that bond and may, where it does grave harm, become a pernicious and mortal lie. Even a kindly "white lie" to spare feelings remains at least a venial sin to be confessed and amended.

Is lying a sin?

Yes, lying is always a sin, by its very nature. The Catechism of St Pius X calls it "a thing evil in itself," and St Thomas Aquinas teaches that a lie is "essentially and formally" a sin against truth (Summa Theologiae, II-II, q. 110, a. 3). Because the disorder lies in the act itself, no good intention can make a lie lawful.

Is lying a mortal sin?

It depends on the kind of lie and the harm it does. The jocose lie (told in jest) and the officious lie (the "white lie") are venial sins; the pernicious lie that "does wrong to one's neighbour" is a mortal sin when the harm caused is grave (Catechism of St Pius X, Part III, ch. 3). But the Roman Catechism warns that "from the lie in jest to the grave lie, the slope is very steep."

What does the Bible say about lying?

The Bible treats lying with great severity. Solomon counts "a lying tongue" among the seven things God hates (Proverbs vi. 16-19), and the Apocalypse places "all liars" among those whose "portion" is "the pool burning with fire and brimstone" (Apocalypse xxi. 8). Scripture sets the liar in the company of murderers and idolaters, never as guilty of a small fault.

Is it ever okay to lie to protect someone?

No. The Church follows St Augustine without flinching: "we must be useful to no one by a lie" (Roman Catechism, Part III, ch. 36). The end does not justify the means, and we may not do even a small evil that good may come of it (Romans iii. 8). What is lawful instead is silence, refusal to answer, or careful speech that withholds what the hearer has no right to know.

What is mental reservation, and is it lying?

A mental reservation is not a lie. It speaks words true in themselves while withholding part of the truth from one who has no right to it — as the servant who says "He is not at home" of a master who will not receive a caller. St Thomas teaches that we are never bound to utter the whole truth, but we are always bound never to assert the false (Summa Theologiae, II-II, q. 110). Where there is a duty to speak plainly — under lawful oath, to a confessor — no reservation is permitted.

What is the Eighth Commandment?

The Eighth Commandment is "Thou shalt not bear false witness against thy neighbour" (Exodus xx. 16). It forbids not only lying but detraction, calumny, flattery, rash judgment, and suspicion, and it commands us "to tell the truth when we must, and to interpret in a good sense, as far as we can, the actions of our neighbour" (Catechism of St Pius X, Part III, ch. 3). One who has sinned against it must also retract his calumny and repair the damage he has caused.

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Sources. Catechism of St Pius X, Part III, ch. 3 (The Commandments which concern our Neighbour — The Eighth Commandment); Roman Catechism (Catechism of the Council of Trent), Part III, ch. 36 (On the Eighth Commandment), citing St Augustine, Contra Mendacium and De Mendacio; St Thomas Aquinas, Summa Theologiae, II-II, q. 109 (on the virtue of truth) and q. 110 (on lying); Exodus 20; St John viii. 32, 44 and xiv. 6; Genesis iii. 4; Proverbs vi. 16-19 and xii. 22; Apocalypse xxi. 8; Romans iii. 8; 1 St John iv. 8 (Douay-Rheims).