Do you know what really grinds my gears? Finding parish or youth group websites posting lists of mortal sins. Not only does no such list exist in the magisterial teaching of Catholic Church, it would be impossible to make one.
For starters, as I discussed in a previous video, there is no such thing as an act that always bears culpability. The act itself is important, but one must always consider the intent of the actor and the circumstances in which they acted.
On top of that, for something to be a mortal sin, it must have more than just “grave matter.” Simply being serious (or what these homemade lists believe to be serious) isn’t enough. There must also be full knowledge and complete consent on the part of the actor. If they don’t know what they’re doing or are not completely free to say no, it cannot be a mortal sin.
Again, for those sitting in the back. Just because someone has done something grave doesn’t make it a mortal sin. In fact, there are many times in which it isn’t.
So when you see a list suggesting that illegal drug use, theft, gossip, anger without justification, superstition, and pride are all mortal sins, without any reference to intent, circumstances, knowledge, or freedom, please remember what the Church actually teaches. There is no such thing as something that is always a mortal sin no matter the circumstances. There are things that consist of grave matter, yes, but that’s not the same as being sinful, and it most certainly isn’t the same as culpability.
Breaking In The Habit 
Father, I have been subscribed to your videos for most of the five year journey. I “found you” when I was in RCIA in the process of converting from Judaism and found your simple direct explanations to be perfect for me as a learner. I have loved watching you grow as a videographer and as a priest and you have helped me grow as a Christian and a Catholic. I look forward to your postings and I now forward them on to others who can benefit from your explanations – or your questions.
You are doing God’s work on earth. Keep going – he needs our hands for now. He left us with work to do.
Fr. Casey,
Thanks for this video! I have often grappled with this question, and the lists that are sometimes made, as you say. I have heard it taught that the very early Christians only had approximately three mortal sins: Murder, Adultery, and Apostasy. I can see how all of those fit in your brilliant analogy of being unable to approach the dinner table.
I think it would ease a lot of minds and hearts if more Church teachers emphasized that most acts are on the level of venial, and maybe even ritual impurity, rather than mortal.
And what about emphasizing underlying patterns of behavior rather than individual acts?
These are just ruminations rather than a directed question or comment. But I’d appreciate any thoughts you happen to have.
Thanks again for your work!