Requirements for a sin to be mortal?


What are the requirements for a sin to be a mortal sin. Do all requirements have to be met?

To be clear, by “mortal sin” I mean “if you do one of these but don’t repent than you go to hell” type of sin.


There are 3 conditions to satisfy.
The sin must be of grave matter, you must know it is of grave matter but you go ahead and commit the sin in that knowledge.


Compendium issued by Pope Benedict XVI

  1. When does one commit a mortal sin?


One commits a mortal sin when there are simultaneously present: grave matter, full knowledge, and deliberate consent. This sin destroys charity in us, deprives us of sanctifying grace, and, if unrepented, leads us to the eternal death of hell. It can be forgiven in the ordinary way by means of the sacraments of Baptism and of Penance or Reconciliation.

  1. When does one commit a venial sin?


One commits a venial sin, which is essentially different from a mortal sin, when the matter involved is less serious or, even if it is grave, when full knowledge or complete consent are absent. Venial sin does not break the covenant with God but it weakens charity and manifests a disordered affection for created goods. It impedes the progress of a soul in the exercise of the virtues and in the practice of moral good. It merits temporal punishment which purifies.

More in the Catechism


Bear in mind that “doing it anyway” is not the same as “with full consent.”


Yes it is. If you know a sin is of grave matter and you then commit it that is a mortal sin.
“Full consent” is not complicated. Assuming you are not coerced or somehow mentally incapacitated then committing a sin you know to be of grave matter is a mortal sin.


So to be clear, if one of the three conditions is missing than that means the sin is not bad enough to land you in hell?

Does this apply to all sins?


Hello Thistle,

Our Catechism does explain that “full knowledge” must be present. But what do you really mean when you say, “you must know it is of grave matter?”

It seems that some could misunderstand this and it can quickly lead to the notion that is becoming more and more popular that practically nobody is going to Hell. Why? Well because very few people really believe that what they are doing is going to lead them there. Most of us rationalize our own grave sin. We make it okay for us.

Does the homosexual “couple” in a sexual relationship know that their relationship is a gravely sinful matter?

Does the person who is raping an 8 year old know that it is a gravely sinful matter?

Does the spouse who abandons their marriage know that it is a gravely sinful matter?

The answer to all three of these most often is that they do not admit it is a gravely sinful matter. So, does that mean that they do not have “full knowledge?”

No. These things are offenses against the natural law so they are written on the hearts of every human. No human will be able to stand in front of God with a “get out of Hell free” card that says, “But, but, but I didn’t know the homosexual relationship, rape or divorce was against Your law!!”


Remember we are talking about Catholics. Put simply, if you know the Church teaches an act is a sin of grave matter and you go ahead and commit the act (excluding coercion or mental incapacity) you commit a mortal sin.


What do you mean by all sins? Venial sins do not land you in Hell.
The three conditions apply to mortal sins and yes all three conditions must be satisfied for it to be a mortal sin.


The full knowledge - does not need to be in theological terms. One does not need to call it “grave matter” or know the theology of mortal sin to commit murder etc and be culpable of it.

As you note natural law is involved.

But also note from the Compendium issued by Pope Benedict XVI :

  1. In what does the natural moral law consist?


The natural law which is inscribed by the Creator on the heart of every person consists in a participation in the wisdom and the goodness of God. It expresses that original moral sense which enables one to discern by reason the good and the bad. It is universal and immutable and determines the basis of the duties and fundamental rights of the person as well as those of the human community and civil law.

  1. Is such a law perceived by everyone?


Because of sin the natural law is not always perceived nor is it recognized by everyone with equal clarity and immediacy.

Also we it is important to remember that while God can work in ways we do not know for those who through no fault of their own do know Jesus Christ --do not know the Gospel and thus discover true life – the normal course is hearing and believing the Gospel -and receiving true life in Christ.


The Church though does not use those words exactly. The terms used are “complete consent” or “deliberate consent”. Which is better for such tends to confuse some that mortal sins are only “things we do in action”.

But yes that is one way to commit a mortal sin.

It is important to note for readers that mortal sin is not only consisting of exterior acts. One can commit mortal sin via omission or via purely interior sin. Of course the deliberate consent needs to be there for such as well.


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