What is the difference between VENIAL and MORTAL sin?
Mortal sins are sins which break our relationship with God, and venial sins are sins which damage but do not break our relationship with God. We are not damned by venial sins, but the more of them we commit the weaker our relationship with God becomes and the easier it is for us to fall into mortal sin. So I would not view venial sins as minor, or not a big deal. All sins are a big deal. Venial sins can’t be the cause of damnation in and of themselves, but they can weaken us to the point where we choose to do something that WILL cause our damnation if we do not repent for having done it. That’s a pretty big deal.
But WHO decides which sin is Venial and Mortal?
God tells us via the Church the criteria for what constitutes a mortal sin.
Generally, my sins are related to the sin of LUST, where unclean thoughts are made. Is anyone Harmed by this? Has anyone suffered because of this kind of sin? So there should be a checklist of questions to determine whether a sin is Venial or Mortal. If I do something that is not harming anyone or anything, it should be considered NO BIG DEAL and washed away as VENIAL, allowing me to receive Communion as normal.
There are three criteria for determining if a sin is mortal:
- The sinful act must be grave matter, defined by the catechism in paragraph 1858 as a violation of one of the Ten Commandments
- The sinful act must be known to be sinful
- The sinful act must be freely chosen in light of the knowledge that it is sinful
All three criteria must be met for a sin to be mortal.
The words of Jesus Christ in Matthew 5:27-28 tell us whether thoughts are harmful:
You have heard that it was said, ‘You shall not commit adultery.’ But I say to you, everyone who looks at a woman with lust has already committed adultery with her in his heart.
Adultery is a violation of the Sixth Commandment, and therefore grave matter. So if you lust in your heart, if you know that adultery is sinful, and yet you still
choose to think those thoughts, then you sin mortally.
Of course, a distinction must be made between urges or fleeting thoughts and
deliberately chosen thoughts. If an urge or thought toward something sinful just pops into our head, then that’s not a sin but a temptation. We didn’t choose to think it. But if we dwell on that urge or thought, if we welcome it, if we actively choose to think it while knowing we should not, then and only then are we sinning. And if it’s grave matter, as is the case with freely chosen lustful thoughts, we have probably crossed the line into mortal sin.
So it’s pretty straightforward. Are you choosing to think these lustful thoughts? If you are not, then you are being tempted but resisting that temptation. On the other hand, if you are choosing to think these thoughts, then you are failing to resist temptation and quite possibly need to go to confession. I can’t tell you which it is, as I’m not the judge of people’s souls and wouldn’t want to be even if it was possible that I could. I’m more than happy to leave the judging to God.
Regardless, I would encourage you to not think of any sin, even the tiniest of venial sins, as no big deal. If we do that, it’s far too easy to wind up giving in to temptation.