Is It a Mortal Sin if I Didn’t Know?

 (Homily for October 29^th 2023)

In one of my homilies I pointed out that we should not receive holy Communion in a state of a mortal sin. The question becomes then, “What is a mortal sin?”

A mortal sin is a seriously bad action, not simply a bad action. This action is seriously bad not only because of what you do, but especially because you do it on purpose, that is, you know perfectly that this is seriously bad and you freely choose to do it anyway. Traditionally, we say the same thing in the following way: a mortal sin requires grave matter (what you do is seriously wrong), full awareness or consciousness (you know that what you do is seriously wrong) and full consent (you choose to do it freely, despite knowing that it is seriously wrong).

Let us set the matter aside, for today, and let us focus on one of the other two subjective characteristics of a mortal sin: full awareness. You cannot say that there is a mortal sin when you do not know that what you are doing is seriously bad. For example, a man who thought he was shooting a deer and kills another hunter instead. If he had known, he would have never shot.

1.  Sometimes, however, you didn’t know but you should have known: like a doctor who kills a patient because he didn’t study carefully how to proceed with the surgery. In this case, the person is still guilty of a mortal sin because they did know that not studying carefully could lead to innocent people being killed.

Other times, you didn’t know but you could have known: for example, when someone had reasons to believe that contraception (cf. Catechism of the Catholic Church, n. 2370) was seriously sinful but they preferred not to find out. True, this person didn’t know but he or she did not want to know and had reasons to suspect that this action was mortally sinful. This person accepted the possibility of committing a mortal sin: this person preferred taking the risk rather than finding out what was the right thing to do. This ignorance does not make this person innocent.

Ignorance excuses from mortal sin when ignorance itself is not sinful. Therefore, if I did something seriously bad because I didn’t know, but I should have known, then I committed a mortal sin. Also, if I had reasons to suspect that something I was going to do was seriously wrong, and I could have found out but I chose not to, then this ignorance does not excuse me from committing a mortal sin. Instead, if it was impossible or very difficult for me to know, then I am innocent.

2.  Full awareness also means that, in order to commit a mortal sin, I need to know that it is a mortal sin before doing it, not afterwards. Sometimes I ask people: “When did you realize it was a mortal sin?” And they say, “A few years after doing it, when they told me.” And I say, “But, could you have possibly known that it was a mortal sin before doing it?” “No, father, how? Actually, they had taught me the opposite and it did not even occur to me that those who taught me could be wrong. I would have never done it if I had known that it was wrong.” This person is innocent.

3.  Finally, full awareness means that I am fully awake and fully aware of the circumstances which make the present action a seriously bad action. For example, things which people do when they are half-asleep may not be mortal sins because of lack of full awareness.

Now, when someone is under the influence of a certain substance, they also lack full awareness: but there is a difference between the one who, for example, gets drunk on purpose and the one who is taking a strong medication because they have to. If you get drunk and then kill someone in a traffic accident because you were driving under the influence, you are responsible, because you knew that getting drunk could expose you to do seriously bad things. You didn’t know what you were doing when you were driving, but you did know what you were doing when you were drinking. Now, suppose that a person under the influence of a prescribed strong medication seriously offends their caregiver: this person may still be innocent, because they were not fully aware of what they were doing.

-  In summary, for a seriously bad action to be a mortal sin, full awareness is necessary. When someone is not completely aware of what they are doing, and they are not guilty of this lack of full awareness, they are not guilty of mortal sin. People are not guilty of being half asleep when they are trying to sleep but they are usually guilty of getting drunk. People are not guilty of ignoring what they could not possibly have learned, but they are guilty of ignoring what they should have known before acting. Choosing ignorance in order to do something at more ease and without remorse does not excuse us from mortal sin: in this case, we are guilty of our ignorance and consequently of the seriously bad action we may commit.

A good conscience is a treasure we must search for. A good conscience is not one who is searching for sin everywhere. A good conscience helps us discovering our own sins, even those we are afraid to acknowledge, so that we may be freed from their burden. A good conscience exposes our sins not to the sight of human beings for our shame, but to the light of God for our healing. Most importantly, a good conscience does not condemn us when we are innocent, and does not blame us for a mortal sin when we have just committed a venial sin. May God give us a good conscience, one that help us to not sin against our dear Lord and to be sorry for our past sins.