Is missing Mass occasionally really a mortal sin? I have heard it is and can not understand why? To never go, yes. But to miss here and there, I don’t have a problem with it.
Hopefully this will help you to understand.
Missing Mass without a good reason is indeed a grave matter. It is specifically stated in the Catechism, it has been taught since the beginning of Catholicism itself, that one attended Mass on all Sundays and holydays of obligation.
Now: Suppose you miss Mass because you are traveling on a tour bus. The bus can’t stop; it has a deadline to meet. Even if you go past a Catholic Church on the way, you physically cannot stop to attend Mass. It is not a grave sin though because you really physically could not get there due to the nature of the bus trip.
Or suppose you are feeling ill. If you are ill enough to stay home from Mass, and then stay home from anything else, including going out to a friend’s, going shopping, going for a stroll, etc., because of feeling ill, again, it is not sinful.
Suppose you have a small child to care for, and it’s cold outside. As a prudent adult, you decide it will be healthier and safer for the child to stay at home, and not risk getting chilled, getting exposed to colds and flu, even getting into an accident traveling if a sudden snow squall or ice event comes through. That’s not sinful.
But. . .to wake up on a Sunday morning and think, "Oh, I am tired out from all the responsibilities of the last week. I had to go to work, I had to cook meals, I had to shop and clean. . .and now here is Mass coming up. . .I don’t WANT to get up now and stop my relaxing, and HAVE to go. I would rather just ‘love Jesus’ and not have to be ‘forced’ into going. Plus I’ll just be upset all through Mass and not paying attention. It’s just dumb’… . .
Now missing for those reasons is gravely wrong and sinful. You’re not ill, you don’t have a child to care for, you can physically get to Mass. . .and you SHOULD. Because Mass is your chance every week to participate WITH CHRIST in His ministry to others, to actually RECEIVE Him, Body and Blood, Soul and Divinity; to be with Him at the cross, to hear His word, to celebrate and thank and praise Him in His own ‘place’. People throughout history have traveled hundreds of miles, sacrificed time and money, have begged, pleaded, and even DIED for the CHANCE to attend ONE Mass, because they knew how important Mass is to our souls.
So yes, to just ‘blow off’ the occasional Mass for selfish reasons of “I just don’t want to go” is gravely (mortally) sinful, despite how a person ‘feels’. “Feelings” are a very poor guide for the truth of any given action. Plenty of sinful things feel really GREAT and plenty of VIRTUES feel like a chore and a bore. . .but as a Catholic Christian you should be following Christ, right? Did He go around doing sinful things and avoiding doing good even it was wearying, boring, tiresome --even when He DIED for it?
Sure, Jesus understood how hard it is for us to be good, but you’ll notice He never forgave people with, "That’s all right, just keep on sinning and I’ll forgive you’.
He forgave those who were SORRY for their sins, NOT those who were NOT sorry. And He didn’t say, "You’re forgiven, do what you want’ but “You are forgiven, go and SIN NO MORE.”
Words to live by.