Mass attendance is required for all Catholics on Holy Days of Obligation.
Missing Mass, whether intentional or not, (except for a serious reason such as sickness) on a Holy Day is considered to be a mortal sin. Those who have committed a mortal sin must go to confession before receiving the Eucharist, because receiving the Eucharist with unconfessed mortal sin on the soul is also a mortal sin.
Many people do not make Mass on these days, and the most common two reasons I hear are variations “I couldn’t get off work” and “I was too busy.” I have tried to accommodate as many schedules as possible with the Mass schedule, but if you can’t make any of our Mass times, please go to another parish. There are Mass times all through the day, all over town. You might have to do a little work to find one that fits, but there are enough different times that everybody can find one.
I also sometimes hear, “It’s not that big of a deal to miss a Holy Day, I’m going Sunday anyway.” However, the Church teaches us that missing Mass on these days is a grave sin, so the Church thinks missing Mass on these days is a big deal. Holy Days celebrate the most important feast days of our faith. The Assumption is a Marian feast, for example, but it also gives us hope for our own resurrection, body and soul, at the end of time. The Church, in teaching that we must go to Mass on Sundays and Holy Days, is teaching us that the Sabbath is fulfilled by our celebration of the Resurrection on Sundays and the mysteries of the faith as presented on the Holy Days.
Even then, we might not see this as a major problem, but the Church is clear: Those who fail to keep these days commit grave sin. (CCC 2181) Why? To sin is to commit an evil act, one that does not have its source in God. When we sin, we are saying to God, “I do not desire to be united to you.” Mortal sins shout that message so loudly that we end up severing the relationship with God.
This is a problem, though, because we cannot reach God on our own. Remember the parable of the rich man and Lazarus: there is a chasm between the two that no human can cross. Similarly, there is a chasm between us and God that we do not have the ability to cross. Only God is able to cross over it. When we cut our connection to God through mortal sin, we have lost our lifeline to reach him. The only way we can get it back is for God to throw us a new one. Luckily for us, God has also given us the sacrament of confession, where he, following the analogy, throws us a new life line and reconnects us with him.
So why does the Church say missing Sunday Mass or a Holy Day is a mortal sin? Because we are commanded to love God, who created us. Part of loving God is giving him worship to him, and this is done by participating in the Sacrifice of the Mass. So, when we intentionally or negligently fail to worship God by participating in Mass on Sundays and Holy Days, it is saying to God that I love something else more than him. This violates the first and most important commandment, to love God with all of our heart, mind, soul, and strength.
Finally, why does the Church teach that those who have committed mortal sins should not receive the Eucharist? When we receive the Eucharist, we not only receive the Body, Blood, Soul, and Divinity of Jesus Christ, but we also renew our baptismal covenant and express communion with God and the communion of saints. If we are in a state where we have separated ourselves from God (mortal sin), we cannot also be in communion with him through the Eucharist. To receive the Eucharist in this state is a lie both to ourselves and to God. St. Thomas Aquinas says that this is a sacrilege and that this lie profanes the Eucharist, both of these are considered mortal sins, because they are offenses against God himself. This helps us to understand why St. Paul writes that “if anyone eats this bread or drinks this cup of the Lord unworthily, he will be held to account for the Lord’s body and blood. A man must examine himself first, and then eat of that bread and drink of that cup; he is eating and drinking damnation to himself if he eats and drinks unworthily, not recognizing the Lord’s body for what it is.” (1 Cor 11:27-29) In fact, St. Paul says that this is not only causing spiritual issues–and damnation is the greatest possible spiritual issue you can have–but it is also causing physical issues. He continues “That is why many of your number want strength and health, and not a few have died.” (1 Cor 11:30)
I hope that this helps you understand the importance of attending Mass on Sundays and Holy Days, the problem of mortal sin, and the need to be reconciled with God of any mortal sin before receiving the Eucharist.
Fr. Matt