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What’s considered a mortal sin?

A mortal sin is a gravely sinful act, which can lead to eternal damnation if a person does not repent before death. For a sin to be mortal, it must meet three conditions:

What are the conditions for a mortal sin?

According to the Catholic Church, for a sin to be mortal it must meet three conditions:

  1. Mortal Sin Must Be Serious: The act itself must be intrinsically evil and grave matter.
  2. Mortal Sin Must Be Committed With Full Knowledge: The person must know that what they’re doing is a mortal sin.
  3. Mortal Sin Must Be Committed With Deliberate Consent: The person must freely choose to commit the act. It can’t be forced.

So for a sin to be mortal all three conditions must be met. First the matter must be grave, then the person must know it is grave matter, and finally they must freely choose to do it anyway.

What constitutes “grave matter”?

According to the Catechism of the Catholic Church, grave matter involves acts that violate the Ten Commandments and the moral law. Specifically, grave matter includes:

  • Murder
  • Adultery
  • Fornication
  • Theft
  • Perjury
  • Bearing false witness

Actions that directly violate the Ten Commandments or natural moral law are considered intrinsically evil. They are grave matter in and of themselves.

Other acts may also be considered grave matter if they significantly harm a person, the community, or the soul. This includes things like drunkenness, drug abuse, domestic violence, etc.

What are some examples of mortal sins?

Here are some specific examples of acts that the Catholic Church considers grave matter and potentially mortal sins if the other conditions are met:

  • Murder or assisted suicide
  • Procuring an abortion
  • Using contraception or getting sterilized
  • Raping someone
  • Committing adultery
  • Fornication (sex outside of marriage)
  • Missing Mass on Sundays or Holy Days of Obligation without a serious reason
  • Theft, robbery, or fraud
  • Getting drunk
  • Doing illegal drugs
  • Pornography
  • Divorce and remarriage without annulment
  • Deliberately harboring hatred or jealousy
  • Cheating people out of money
  • Physically harming others in anger

Again, for these acts to actually be mortal sins the person would need to know they are seriously wrong but make the choice to do them anyway out of their own free will.

What are the consequences of mortal sin?

If left un-repented, mortal sin results in eternal punishment in Hell. By committing a mortal sin, a person rejects God and turns away from Him. It severs the person’s relationship with God and the Church.

Some specific consequences of un-repented mortal sin include:

  • The loss of sanctifying grace – the supernatural life of the soul
  • The loss of the theological virtues of faith, hope, and charity
  • The loss of other supernatural gifts of God like joy and peace
  • The loss of the right to enter the Kingdom of Heaven (eternal damnation in Hell)
  • Exclusion from the sacraments, especially Holy Communion

However, even mortal sin can be wiped away with true contrition, a sincere confession, and doing penance.

Can mortal sin be forgiven?

Yes, mortal sin can be wiped away through the Sacrament of Reconciliation (also called Confession or Penance). For a sin to be forgiven, the person must:

  1. Make an examination of conscience
  2. Be contrite and repentant of their sins
  3. Confess their sins to a priest
  4. Receive absolution from the priest
  5. Do the penance assigned by the priest

After completing this process, sanctifying grace is restored to the person’s soul and they are once again in full communion with God and the Church. The eternal punishment for mortal sin is removed.

However, there may still be temporal punishments due for sins on earth, in purgatory, or in this life.

How can you avoid mortal sin?

Here are some tips for trying to avoid mortal sin in your life:

  • Pray and cultivate your relationship with God daily
  • Receive the sacraments frequently, especially Reconciliation and the Eucharist
  • Spend time reading Scripture and spiritual writings
  • Follow your conscience and make morally sound choices
  • Avoid temptation and situations that could lead you to sin
  • Examine your conscience regularly for venial sins too
  • Ask for the grace to persevere and grow in virtue

Having a strong prayer life centered on Christ and the sacraments provides the grace to overcome temptation and avoid serious sin.

What is venial sin?

In contrast to mortal sin, venial sin is a lesser sin that does not destroy sanctifying grace in the soul or totally sever the relationship with God. However, venial sin does weaken grace in the soul and damages the relationship with God.

Some key things to know about venial sins:

  • Venial sins often stem from human weakness, ignorance, or confusion.
  • Venial sin involves a more minor violation of the moral law or something not entirely forbidden.
  • Examples include small lies, impatience, pride, and indecent thoughts.
  • Venial sin weakens the soul’s ability to resist mortal sin.
  • Venial sins can lead to situations that enable mortal sin.
  • Many venial sins over time can make us more prone to grave sin.

Although venial sins do not cut us off from sanctifying grace, Scripture warns that God still takes them seriously. So we should strive to avoid all sin even if just venial.

Can you commit a mortal sin accidentally?

For a sin to be mortal, there must be full knowledge and deliberate consent. So in general, it’s not possible to accidentally commit a mortal sin.

However, exceptions include:

  • Willful ignorance – Avoiding learning something is sinful so you can do it anyway.
  • Acting in reckless disregard – Doing something so risky you should know it could be mortally sinful.
  • Doubting but committing it anyway – Being unsure if something is a mortal sin but doing it anyway without checking.

In these cases, a person’s culpability may not be reduced even though they didn’t directly intend the gravity of the act. So it could still potentially be considered a mortal sin.

If you accidentally commit an act you later realize is mortal, you must confess it and receive absolution to have the sin forgiven.

Are some mortal sins worse than others?

Since mortal sin destroys sanctifying grace, in one sense all mortal sins are equal in effect. However, some mortal sins are considered worse than others based on Scripture, tradition, and moral principles.

According to Catholic teaching, mortal sins can differ in their gravity based on:

  • Matter: Some matter is graver than others, like murder vs. theft.
  • Effects: Sins that do more harm are worse.
  • Circumstances: Sins done out of hatred are worse than out of passion.
  • Who is affected: Sins against the innocent are worse.
  • Frequency: Habitual sin is worse than one act.

Based on these criteria, some mortal sins like murder and adultery are considered graver and more dangerous than others like a single lie. But in the end, all mortal sins cut off grace and require confession.

What’s the “unforgivable” mortal sin against the Holy Spirit?

There is one particular mortal sin that is deemed unforgivable – the sin against the Holy Spirit. This involves fully rejecting God’s love and grace. The Catechism defines it as:

There are no limits to the mercy of God, but anyone who deliberately refuses to accept his mercy by repenting, rejects the forgiveness of his sins and the salvation offered by the Holy Spirit.

According to the Church, this sin against the Holy Spirit consists of fully knowing and willfully rejecting God’s love and forgiveness by stubbornly refusing to repent of sin and turn to God for mercy. It is knowingly and definitively shutting out God’s grace.

Some key things to know about this “unforgivable” sin:

  • It involves total defiance and entrenched hatred of God.
  • It is rejecting mercy itself.
  • It can only be committed by someone old enough to understand what they are doing.
  • It is very rare because most have some openness to repent.
  • If worried you committed it, you clearly have not shut out God.

In the end, no one but God can determine if a person has committed this unforgivable sin. But it remains possible to repent from any other mortal sin.


In summary, mortal sin is a grave violation of God’s law that destroys sanctifying grace. For it to be mortal, the matter must be serious, the person must know it is serious, and it must be committed with full consent. Though mortal sin cuts us off from God, He offers forgiveness through the Sacrament of Reconciliation. While we should strive to avoid all sin, even venial, through God’s grace we can overcome our human weaknesses.