Mortal Sin and Venial Sin: What the Catholic Church Teaches

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A mortal sin is a grave sin committed with full knowledge and deliberate consent; it destroys the life of grace in the soul. A venial sin is a less serious sin, or a grave one committed without full knowledge or consent; it wounds our friendship with God but does not break it. The Catechism of the Catholic Church explains the difference in paragraphs 1854–1864.

This guide sets out the Church’s teaching in plain language, with the Catechism’s own words, the examples it gives, and practical help for anyone worried about the state of their soul. Above all, remember that no sin is greater than God’s mercy.

The difference at a glance

Mortal sinVenial sin
MatterGraveLess serious (or grave, without full knowledge or consent)
Effect on the soulDestroys charity and the state of graceWeakens charity but leaves grace in place
Relationship with GodTurns a person away from GodOffends and wounds the relationship
ForgivenessNormally through the sacrament of Penance (Confession)Through contrition, prayer, the Eucharist and good works; Confession is recommended
Holy CommunionMust go to Confession firstMay receive Communion

The Catechism puts it this way: “Mortal sin destroys charity in the heart of man by a grave violation of God’s law… Venial sin allows charity to subsist, even though it offends and wounds it” (CCC 1855).

The three conditions for a mortal sin

For a sin to be mortal, all three of these conditions must be met together (CCC 1857):

  1. Grave matter. The act itself is seriously wrong. The Catechism says grave matter “is specified by the Ten Commandments” (CCC 1858).
  2. Full knowledge. The person knows the act is sinful and opposed to God’s law (CCC 1859).
  3. Deliberate consent. The person freely chooses it; the consent is “sufficiently deliberate to be a personal choice” (CCC 1859).

If one of the three is missing, the sin is not mortal, though it may still be a venial sin. This matters: a person who acts out of genuine ignorance, or under strong pressure, fear, addiction or illness, may bear less guilt or none. The Catechism says such factors “can diminish or even remove the imputability of a grave offense” (CCC 1860). At the same time, “feigned ignorance and hardness of heart” do not lessen guilt but increase it (CCC 1859).

Examples of grave matter named in the Catechism

The Catechism does not give a complete list of mortal sins, because the other two conditions depend on the person. It does name many acts as grave matter. Some examples:

  • Against God: blasphemy and perjury (CCC 1856); deliberately missing Mass on Sundays or holy days of obligation without a serious reason (CCC 2181); receiving Holy Communion while conscious of a grave sin (CCC 1385).
  • Against life: murder (CCC 1856, 2268); abortion (CCC 2271–2272).
  • Against marriage and chastity: adultery (CCC 1856, 2380–2381) and other acts the Catechism calls gravely contrary to chastity.
  • Against neighbor: serious theft, fraud and injustice, and lies or false witness that do grave harm (CCC 1858).

The Catechism notes that gravity varies: “murder is graver than theft,” and who is harmed also matters (CCC 1858). For a full, gentle walk through the commandments before Confession, use our examination of conscience or the Ten Commandments guide.

What makes a sin venial

The Catechism says a person commits venial sin “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).

Everyday impatience, small lies that do no serious harm, unkind remarks, laziness in prayer and minor selfishness are typical venial sins. They should not be shrugged off. Venial sin “weakens charity,” and “deliberate and unrepented venial sin disposes us little by little to commit mortal sin” (CCC 1863). But it “does not break the covenant with God” and, with God’s grace, “it is humanly reparable” (CCC 1863).

Where the distinction comes from

The Church teaches that the difference between mortal and venial sin is “already evident in Scripture” and “corroborated by human experience” (CCC 1854). The clearest text is in St. John’s first letter:

He that knoweth his brother to sin a sin which is not to death, let him ask, and life shall be given to him, who sinneth not to death. There is a sin unto death. (1 John 5:16, Douay-Rheims)

The word mortal comes from the Latin for “deadly”: it kills the life of grace. Venial comes from venia, “pardon”: it is more easily forgiven.

How mortal sin is forgiven

Because mortal sin attacks charity itself, it “necessitates a new initiative of God’s mercy and a conversion of heart which is normally accomplished within the setting of the sacrament of reconciliation” (CCC 1856). In practice:

  1. Go to Confession as soon as reasonably possible. Confess each mortal sin you remember, in kind and approximate number.
  2. Make an act of perfect contrition right away. Sorrow that comes from love of God above all, together with the firm intention to go to Confession, obtains forgiveness even before you reach the confessional (CCC 1452). See the Act of Contrition.
  3. Do not receive Holy Communion until you have been to Confession. “Anyone conscious of a grave sin must receive the sacrament of Reconciliation before coming to communion” (CCC 1385).

How venial sin is forgiven

Venial sins are forgiven by sincere sorrow, prayer, acts of charity and above all by Holy Communion, whose “living charity wipes away venial sins” (CCC 1394). The Penitential Act at the start of Mass is also a moment to ask pardon for them.

Confession of venial sins is not strictly required, but the Church “strongly recommends” it, because it helps form our conscience and heals our weaknesses (CCC 1458). Many Catholics go to Confession monthly for this reason.

If you are unsure whether a sin was mortal

This is a common worry, especially for people with a tender or anxious conscience.

  • Do not try to settle it alone. Mention it in Confession and let the priest help you judge.
  • Remember the three conditions. If you were not sure it was seriously wrong, or you did not fully consent, it may not have been mortal.
  • If you struggle with constant doubts (scrupulosity), ask a priest to be your regular confessor and follow his guidance, even when your feelings disagree.
  • Never stay away from God out of fear. The Catechism reminds us that while we can judge an act to be gravely wrong, “we must entrust judgment of persons to the justice and mercy of God” (CCC 1861).

Frequently asked questions

Is missing Sunday Mass a mortal sin?

Deliberately missing Mass on a Sunday or holy day of obligation without a serious reason is grave matter (CCC 2181). Illness, caring for infants or the sick, and similar serious reasons excuse a person. See our guide to holy days of obligation.

What is the unforgivable sin?

Jesus speaks of blasphemy against the Holy Spirit (Mark 3:29). The Catechism explains that “there are no limits to the mercy of God,” but a person who deliberately refuses God’s mercy by refusing to repent rejects forgiveness itself (CCC 1864). Anyone who is worried about having committed it clearly has not, because they still want God’s mercy.

Can a mortal sin be forgiven without Confession?

Perfect contrition with the intention of confessing obtains forgiveness (CCC 1452), but the obligation to confess remains, and you should not receive Communion until you have done so. When Confession is truly impossible, as at the point of death, God’s mercy is not bound by the sacraments.

Are the seven deadly sins all mortal sins?

Not necessarily. The seven capital sins (pride, greed, envy, wrath, lust, gluttony and sloth) are tendencies that lead to other sins (CCC 1866). A particular act can be mortal or venial depending on its matter, knowledge and consent.

Related guides

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