Free guide · cited to the Catechism

What Are the Mortal Sins? The Three Conditions, the Seven Capital Sins, and Venial Sin

A mortal sin needs three conditions together: grave matter, full knowledge, and deliberate consent. Learn the seven capital sins and mortal vs. venial sin.

By 1765 Sanctum Co. · Updated July 7, 2026

A mortal sin is a grave violation of God's law that destroys charity in the soul and cuts a person off from God's sanctifying grace. The Catholic Church teaches that three conditions must all be present at once for a sin to be mortal: grave matter, full knowledge, and deliberate consent (Catechism of the Catholic Church 1857). Grave matter is specified by the Ten Commandments — acts such as murder, adultery, theft, and blasphemy. A sin lacking any one of these conditions — through less serious matter, incomplete knowledge, or diminished consent — is instead venial, which wounds but does not destroy the soul's friendship with God (CCC 1862–1863). The Church also names seven "capital sins" — pride, avarice, envy, wrath, lust, gluttony, and sloth — the root tendencies from which other sins grow (CCC 1866).

What is a mortal sin? The Church's definition

The Catholic Church defines mortal sin as a grave, deliberate act that "destroys charity in the heart of man by a grave violation of God's law" (Catechism of the Catholic Church 1855). The word mortal means death-dealing: such a sin turns a person away from God — the soul's ultimate good — by preferring a lesser good in his place, and it brings the loss of sanctifying grace, the very life of God in the soul. This is not a category the Church invented to burden consciences. Scripture itself distinguishes deadly sin from lighter fault: "There is a sin unto death... All iniquity is sin" (1 John 5:16-17). St. Paul likewise warns that those who persist in the "works of the flesh... shall not obtain the kingdom of God" (Galatians 5:19-21). Understanding what actually makes a sin mortal — rather than guessing, minimizing, or despairing — is the first step toward the mercy God freely offers. A careful examination of conscience begins right here.

The three conditions of mortal sin (all three required)

For a sin to be mortal, three conditions must be met together — all at once, not one or two. The Catechism states plainly: "Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent" (CCC 1857).Because all three are required, the absence of any one changes the moral reality. A gravely wrong act done in real ignorance, or without true freedom, is not a mortal sin — though it may still be venial. This is why the Church insists on precision rather than fear: mortal sin is a real and serious possibility, but it is never presumed lightly.

Grave matter vs. guilt: why the two are not the same

It helps to keep two questions distinct: Is the act gravely wrong? (its objective matter) and Is this person fully guilty of it? (subjective culpability). Grave matter is objective — murder, adultery, and blasphemy are serious whether or not anyone feels they are. But guilt depends on knowledge and consent, and the Catechism is careful here: "Unintentional ignorance can diminish or even remove the imputability of a grave offense," and "the promptings of feelings and passions... external pressures or pathological disorders" can reduce the free character of an act (CCC 1860). This teaching guards against two errors. One is minimizing — pretending grave matter is not grave. The other is scrupulosity, the anxious habit of treating every small fault as a damning sin. If you are tormented by the fear that you have sinned mortally when knowledge or consent was genuinely lacking, our guide on Catholic scrupulosity may help. We judge acts, never souls — only God reads the human heart.

Mortal sin vs. venial sin

Not every sin is mortal. The Church teaches that "venial sin allows charity to subsist, even though it offends and wounds it" (CCC 1855). One commits venial sin, the Catechism explains, "when, in a less serious matter, he does not observe the standard prescribed by the moral law, or when he disobeys the moral law in a grave matter, but without full knowledge or without complete consent" (CCC 1862). Venial sin weakens our love for God and neighbor and makes graver sin easier, but it "does not break the covenant with God" and "is humanly reparable" by grace (CCC 1863). Scripture grounds the distinction: St. John writes that "there is a sin unto death" and sin that is "not unto death" (1 John 5:16-17). The practical upshot: venial sins are healed through prayer, penance, the Eucharist, and contrition, while mortal sin calls for sacramental confession. Both matter, and neither should be ignored.

The seven capital sins (the "seven deadly sins")

Popular culture calls them the "seven deadly sins," but the Church's precise term is the capital sins. Following St. John Cassian and St. Gregory the Great, the Catechism lists them: "pride, avarice, envy, wrath, lust, gluttony, and sloth or acedia" (CCC 1866). They are called capital — from the Latin caput, "head" — not because each is automatically a mortal sin, but "because they engender other sins, other vices" (CCC 1866). They name the root tendencies from which particular sins grow. This is a crucial clarification: feeling anger or a flash of pride is not, by itself, a mortal sin. The capital sins are disordered inclinations that, left unchecked, produce sinful acts — and by repetition harden into vice, since "sin creates a proclivity to sin" (CCC 1865). The remedy is not merely avoiding acts but cultivating the opposing virtues — humility against pride, generosity against avarice — through prayer and a steady rule of life.

What mortal sin does — and how it is healed

Left unrepented, mortal sin has grave consequences: it "results in the loss of charity and the privation of sanctifying grace," and "if it is not redeemed by repentance and God's forgiveness, it causes exclusion from Christ's kingdom and the eternal death of hell" (CCC 1861). But notice the condition if it is not redeemed — the same Church that names the wound points urgently to the cure, and the heart of the Gospel is mercy. The ordinary way God restores a soul after mortal sin is the Sacrament of Penance. The Catechism teaches that anyone conscious of grave sin "must receive the sacrament of reconciliation before coming to Communion" (CCC 1385), and that the faithful are bound "to confess serious sins at least once a year" (CCC 1457). No sin is greater than God's mercy. If it has been a long time, take heart — read how to go to confession after years away, then prepare with a thorough examination of conscience and an Act of Contrition.

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Frequently Asked Questions

What are the three conditions of a mortal sin?

According to the Catechism of the Catholic Church, a sin is mortal only when three conditions are met together: grave matter, full knowledge that the act is seriously wrong, and deliberate consent of the will (CCC 1857). If any one of the three is missing, the sin is not mortal, though it may still be venial. All three must be present at the same time.

What are the seven deadly sins?

The "seven deadly sins" are more precisely called the capital sins: pride, avarice (greed), envy, wrath (anger), lust, gluttony, and sloth (CCC 1866). They are called "capital" because they are the source from which other sins spring — not because every instance is automatically a mortal sin. They name disordered tendencies that lead to sinful acts when we freely consent to them.

What is the difference between mortal and venial sin?

Mortal sin destroys charity in the soul and cuts a person off from sanctifying grace by a grave, fully deliberate violation of God's law (CCC 1855, 1857). Venial sin, by contrast, "does not break the covenant with God" — it offends and wounds charity but does not destroy it, and it "is humanly reparable" with grace (CCC 1862-1863). Scripture reflects this in the distinction between "a sin unto death" and sin "not unto death" (1 John 5:16-17).

Can a mortal sin be forgiven?

Yes. No sin is beyond God's mercy for the person who repents. The Catechism teaches that mortal sin excludes from the kingdom "if it is not redeemed by repentance and God's forgiveness" (CCC 1861) — meaning it truly can be redeemed. The ordinary means is the Sacrament of Penance (confession); the Church asks the faithful to confess grave sins before receiving Communion (CCC 1385) and at least once a year (CCC 1457).

Do you go to hell for committing one mortal sin?

The Church teaches that unrepented mortal sin, clung to until death, results in "the eternal death of hell" because it freely and finally rejects God's love (CCC 1861). But a single mortal sin does not doom a person who repents: God's forgiveness, ordinarily through sacramental confession, fully restores the soul to grace. The Church urges neither presumption nor despair, but repentance and trust in God's mercy.

How do I know if I committed a mortal sin?

Ask whether all three conditions were present: Was the matter grave? Did I know it was seriously wrong? Did I freely and deliberately consent? (CCC 1857). If the matter was grave but knowledge or consent was genuinely lacking, the Catechism says imputability can be diminished or even removed (CCC 1860). When you are truly uncertain, bring it to confession rather than judging your own soul — and avoid the trap of scrupulosity. A guided <a href="/examination/">examination of conscience</a> can help you look honestly and calmly.

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Primary Sources

Every doctrinal claim on this page traces to a named primary source — verified against the Catechism (vatican.va), Sacred Scripture, and the Magisterium.

Verified by 1765 Sanctum Co., July 7, 2026. Found an error? [email protected] — errata corrected the day they're found.

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