As it stands now I DON’T know that missing mass is a grave matter. I guess I should say I don’t know why it is a grave matter. The answer I recieved was “mass is a time God commanded us to observe, and to place our own desires above His is sinful.” I agree with this completely, but I don’t understand what makes this a mortal sin. Is breaking any of the 10 commandments a mortal sin? Aren’t we implicitly “commanded” to refrain from any sin? I’m not trying to be obtuse or thick-headed.
Don’t worry, I’m asking these questions because I enjoy learning about my faith, not out of fear about going to hell.
EDIT: spelling correction
I highlighted a portion of your sentence above. The concern I have here is that you stated the “I don’t know that missing Mass is grave matter.” As I stated before - it doesn’t matter what YOU think about this. The Church, through the Holy Spirit and representative of Christ on earth IS TELLING YOU - IT IS GRAVE MATTER! Besides, the “finger of God” wrote it in stone for you!
It is grave matter because God Himself tells you “to keep the Sabbath holy.” That means to set aside one day a week to worship God. He commands that we do that. It’s not a complex thing. Now, if for no “good reason” YOU decide that keeping the Sabbath holy is not important and YOU decide to go do something else, then YOU are deciding that YOU know better than God. How arrogant is that? The answer you received in your above quote is a very good answer. You are placing your own desires above those of God - that is grave matter. God has given us a “map” so to speak, in the 10 commandments, on how to get back to Him. If we choose not to follow that map, then it is of our choosing - not His.
I would say that for the 10 commandments, if you murder or steal, commit adultery or fornication or any of the sexual sins this covers, if you covet what your neighbor has and especially his wife, knowing God has commanded you not to do these things and you did it with full knowledge and consent - then it is mortal sin. I’d say everything covered in the 10 commandments is pretty serious stuff.
As a previous poster said, you have to KNOW, first of all. Defective instruction can keep a person from being guilty of mortal sin. Only God truly knows someone’s heart and soul and only He can make that judgement.
As for the opening line of your post, “As it stands now, I don’t know that missing Mass is grave matter.” You know it is now. You cannot claim ignorance any longer. You may not understand why still, but if you intentionally now do not go to Mass, you will be committing mortal sin. Just because you still do not understand why, does not release you from the guilt. We will help you as much as possible to understand why.
Try some additional reading in your Catechism. It will explain “why” much better. I don’t have my Catechism with me, but look in the index under “Mass” and you should find plenty of paragraphs to read. Even try under “10 Commandments.” The book, “The Lambs Supper” is an absolutely fabulous book! You can find used books on Amazon. That’s where I’ve gotten alot of my books. They are sometimes half the original price (or less).