Just a little note.
Sometimes the terms “grave sin”, “mortal sin” and “serious sin” get used in a way other than the usage of the Church – which can confuse things somewhat.
They are *synonyms *in Catholic moral theology and the documents of the Church.
A grave sin is a mortal sin. A serious sin is a mortal sin. A mortal sin* is* a grave sin.
Sometimes one finds on the forum a writer saying something like --“was this a grave sin or a mortal sin?” Or “the person committed a grave sin but it was not mortal”. which can lead to the impression that a grave sin was anything other than a mortal sin.
Mortal sin and Grave sin the terms for the same sin.
grave sin = mortal sin =serious sin
It is understandable that this gets confused sometimes.
Where the confusion enters in is on the one hand- in order to *commit *a mortal sin (grave sin) one needs grave matter, full knowledge and deliberate consent.
On the other hand it is also completely correct to say things like: murder is a grave sin or adultery is a grave sin --speaking of the thing itself --in itself. Or murder is a mortal sin.
Such is a -grave, serious, mortal -sin (all meaning the same thing but with different accent).
And it is also true to say: “such and such” is a grave sin but I did not commit a grave sin when I did “such and such” for I lacked the needed knowledge or the needed consent so my sin that I committed was *venial *if there was sin.
One can also say ““such and such” is a grave matter but I did not commit the grave sin for I lacked deliberate consent --so I committed a venial sin or no sin.”
That can help keep things more clear in discussing these things (and which is what many do here of course already).
But what one does not want to say is: I committed “such and such” but without the needed deliberate consent or knowledge so I committed a grave sin but not a mortal sin.
Such would be not the right way to put it – for a grave sin* is *a mortal sin. They mean the same thing. Similarly one would not want to say “I committed a serious sin but it was not mortal”.
Best way is likely use the language that does in fact usually get used here: ““such and such” is a grave matter but he did not commit the grave sin for he lacked deliberate consent --so he committed a venial sin or no sin.”
I thought to note it again in a general way for it comes up from time to time.
Here are some short examples of usage in documents of the Catholic Church -others can be given but these are a good example for one sees the terms used together.
From: The Compendium of the Catechism issued by Pope Benedict XVI
- Which sins must be confessed?
All grave sins not yet confessed, which a careful examination of conscience brings to mind, must be brought to the sacrament of Penance. The confession of serious sins is the only ordinary way to obtain forgiveness." (see also Canon Law …the term is used there too).
- What is required to receive Holy Communion?
To receive Holy Communion one must be fully incorporated into the Catholic Church and be in the state of grace, that is, not conscious of being in mortal sin. Anyone who is conscious of having committed a grave sin must first receive the sacrament of Reconciliation before going to Communion.