Ask Fr. Bitaju | Kairos Global | JUNE 2026

Author : Fr. Bitaju

Q. What are mortal sins in Catholic teaching?

In Catholic teaching, mortal sins are serious offences against God that result in the loss of sanctifying grace and the separation from God’s love. The Catechism of the Catholic Church outlines the nature and conditions of mortal sin, emphasising its gravity and the necessity of repentance for reconciliation with God. 

Definition: Mortal sin is defined as a grave violation of God’s law that results in the complete turning away from God. It is a sin that destroys charity in the heart of man by a grave violation of God’s law (CCC 1855).

Three Conditions for Mortal Sin: For a sin to be considered mortal, three conditions must be met. a) Grave matter: The act itself must be intrinsically evil and immoral. For example, murder, adultery, theft, and other serious offences against God’s commandments (CCC 1857). b) Full Knowledge: The person committing the sin must have full knowledge that the act is a serious sin. This means that they are aware of the moral gravity of the act and its consequences. (CCC 1857). c) Deliberate Consent: The individual must give their full consent to the act, meaning that they freely choose to commit the sin without coercion (CCC 1857).

Consequences of Mortal Sin: Mortal sin results in the loss of sanctifying grace, which is the divine life of God within the soul. This separation from God can lead to eternal damnation if not repented. The Catechism states, ‘Mortal sin is a radical possibility of human freedom, as is love itself’ (1861).  

The Need for Repentance: The Church teaches that to be reconciled with God after committing a mortal sin, one must sincerely repent and seek forgiveness through the Sacrament of Reconciliation (confession). The Catechism emphasises the importance of this sacrament for restoring grace: ‘The Sacrament of Penance is the only ordinary way for the faithful to be reconciled with God’ (CCC 1468). 

Distinction from Venial Sin: Mortal sin is contrasted with venial sin, which is less serious and does not sever one’s relationship with God. Venial sins weaken charity and can be forgiven through acts of contrition, prayer, and participation in the Eucharist (CCC 1862).

Pastoral Considerations: The Church recognises that circumstances and psychological factors can affect an individual’s culpability. Thus, while the objective nature of the mortal sin is grave, the subjective guilt may vary based on the individual’s awareness and consent (CCC 1860). 

In conclusion, according to Catholic teaching, mortal sins are serious offenses against God’s law that require grave matter, full knowledge, and deliberate consent. They lead to a loss of sanctifying grace and necessitate repentance and reconciliation through the sacrament of confession.