Yes, it does matter.
Through His Church, God commands us to attend Mass on Sundays and Holy Days of Obligation. It is a mortal sin to miss Mass without a grave reason (such as illness, being housebound, a first responder rushing to a call, etc).
You may wonder why the Church commands weekly Mass attendance under pain of sin, rather than simply suggesting it. It’s important to know why—not only to strengthen our own faith, but also in case any curious non-Catholics ask about it.
The reason for the Sunday obligation is that we owe God worship as His creatures. It’s not just a nice spiritual ritual or an outward show of being Catholic. God is our Creator. He made us out of nothing and keeps us in existence through His own power and will. We owe everything to Him, and our regular worship of Him is how we express our innate desire—and our natural obligation—to offer our Creator homage and gratitude.
Furthermore, without His grace and presence in our lives, our souls and therefore our salvation are in danger. He doesn’t need our worship—but we do need Him.
If we ignore God’s command to worship on Sundays, we are putting other things before God, as though He were of secondary importance. And we are destroying our relationship with Him and walking away from the spiritual graces our soul needs to stay alive. As one priest said, skipping Sunday Mass
is somewhat analogous to a deep-sea diver’s putting a crimp in his air line so that no air can come through to keep him alive. By a decision to miss Sunday Mass or a holy day of obligation we suspend the operation of sanctifying grace in our lives.
—Fr. Ray Ryland, “Why Is It a Mortal Sin to Miss Mass?” at Catholic Answers
God knows that, due to our fallen nature, we struggle to do what we should, feel confused about it, and are even tempted not to. That’s why He gives us clear commandments. The Third Commandment prescribes weekly worship of God: “Thou shalt keep holy the Lord’s day.” And Jesus commanded: “Do this in memory of me” (Luke 22:19).
If Mass on Sunday were just an option—and skipping it were not a sin—can any of us honestly say we would never, ever miss a Sunday Mass?
We—and the Church—know the answer.
Get more answers to important questions in What Catholics Really Believe: 52 Answers to Common Misconceptions About the Catholic Faith. In this easy-to-read Q&A format, Karl Keating offers comprehensive explanations to some of the most frequently-asked questions about Catholicism. An invaluable resource for knowing and defending the Faith! Get your copy today!