What makes a mortal sin?

What makes a mortal sin?

“Bless me Father for I have sinned,” the person began, “I’ve committed a mortal sin.”

I’ve heard this phrase several times when hearing confessions, and it always grabs my attention. Mortal sin is something notoriously difficult to determine in specific cases, even for ourselves. There have even been times when a person has come to me, for example, absolutely convinced that they committed a mortal sin, but I have serious doubts that it is the case.

Why is it so hard to determine the existence of mortal sin? Because mortal sin has two components:

1. A subjective element, in that for a sin to be mortal it requires:
   1. full knowledge that the sin is a sin, including its gravity; and
   2. full consent to the sin itself.
2. An objective element, in that the sin itself must be gravely sinful….the little stuff usually just isn’t heavy enough to keep us out of heaven.

Anything that falls short of these criteria is not a mortal sin, but a venial sin, and therefore is not enough to keep us out of heaven. And because it is so hard to read the subjective element (how can we ever declare we know what is going on in the heart of another? how can we even know with certainty what is going on in our own heart?), it is very hard to declare, with 100% certainty, which actual sins are mortal and which aren’t.

It is possible to abuse this element of moral teaching, by going so far as to say that *no* sin is ever mortal. The argument is that humans are not psychologically equipped to ever really have full knowledge and/or full consent. Some theologians have tried to explain this by proposing that it isn’t the actual sins that count as some sort of transcendental “fundamental option” for or against God, but John Paul II has reminded the Church (through his encyclical Veritatis Splendor) that the way we, in fact, change our fundamental option is in reference to actual sins.

For myself, I am not so sure that “gravely” sinful acts are in fact mortal sins all that often. For those who do wind up in Hell upon their death, I have an intuition that many of them are there not because of the actual sin, but because of their refusal to repent from it. Like I said in a previous post, we can’t change our past, but we can alter how that past is incorporated in our present. This is the essence of repentance, and the refusal to repent is itself a moral choice — and possibly a mortal one, because ultimately it involves that first of all sins, PRIDE. My argument, in essence, is that it is possible to mortally sin in refusing repentance from a sin that is otherwise objectively venial.

This, in fact, is part of why it is important to preach the Gospel. Some people have asked me, “If mortal sin requires full knowledge, isn’t it counter-productive to preach the Gospel? After all, by giving people full knowledge, aren’t you opening a door to mortal sin for them, a door otherwise closed?” Well, maybe. But sin has an alienating effect….from others, from God, even from ourselves. And we want, deep down, to overcome that alienation. Vatican II taught the following:

Often men, deceived by the Evil One, have become vain in their reasonings and have exchanged the truth of God for a lie, serving the creature rather than the Creator. Or some there are who, living and dying in this world without God, are exposed to final despair. Wherefore to promote the glory of God and procure the salvation of all of these, and mindful of the command of the Lord, “Preach the Gospel to every creature”, the Church fosters the missions with care and attention. (Lumen Gentium, no. 16)

“Final despair” is, in a sense, the ultimate mortal sin. And if final despair can be attained without the Gospel, then the Gospel is necessary to rescue people from it. And that is why it must be preached, for the fundamental message of the Gospel — the very first thing Jesus ever preached — was “Repent! And believe the Gospel.”