Question Box: Is missing Sunday Mass a mortal sin?


By Father Thom Hennen
Is it still considered a mortal sin to miss Mass on Sundays without a valid reason?

Fr. Hennen

My experience has been that people tend to be either overly scrupulous or totally unscrupulous about this. Some feel that they will be damned for eternity if they ever miss Sunday Mass, even if they were in the hospital in a coma when there was a blizzard and Mass was canceled anyway. Others casually skip Mass Sunday after Sunday because it just doesn’t work in their schedule; the kids had a tournament, they felt like sleeping in, they were on vacation or their favorite team was playing. Hopefully, you can see how both of these attitudes are misguided.

Before we go further, it may be important to remind people of the distinction between “mortal” and “venial” sin. The scriptural basis for this comes from the first letter of John: “If anyone sees his brother sinning, if the sin is not deadly [i.e. mortal], he should pray to God and he will give him life. This is only for those whose sin is not deadly. There is such thing as deadly sin, about which I do not say that you should [simply] pray. All wrongdoing is sin, but there is sin that is not deadly” (1 John 5:16-17).

The “Catechism of the Catholic Church” defines mortal sin as sin that “destroys charity in the heart of man by a grave violation of God’s law; it turns man away from God, who is his ultimate end and his beatitude, by preferring inferior goods to him.” Whereas, venial sin “allows charity to subsist, even though it offends and wounds it” (par. 1855).


The Catechism goes on to explain that for a sin to be considered mortal, three conditions must together be met: (1) the act itself must constitute “grave matter,” (i.e., a more serious or direct violation of the Ten Commandments); (2) the person must have full knowledge that this is, in fact, gravely sinful; and (3) the person must deliberately consent to the act (par. 1857-1859). In other words, “It was seriously wrong, I knew it was seriously wrong and I chose to do it anyway.”

Incidentally, the Catechism also states, “Anyone who is aware of having committed a mortal sin must not receive Holy Communion, even if he experiences deep contrition, without having first received sacramental absolution, unless he has a grave reason for receiving Communion and there is no possibility of going to confession” (par. 1487). However, this does not mean the person is dispensed from the obligation of attending Mass.

Many Catholics equate “grave matter” with “mortal sin,” but this is not quite correct. We can more objectively judge what constitutes grave matter by looking at the Ten Commandments, and where there are questions about particular sins, often the Church will clarify. Such is the case for deliberately missing Mass without good reason on Sundays and other holy days of obligation unless excused for serious reason (for example, illness). The Catechism says, “Those who deliberately fail in this obligation commit a grave sin” (par. 2181).

What we cannot judge objectively for anyone but ourselves is whether or not a person had full knowledge that a sin was considered gravely sinful or to what degree (if at all) that they deliberately consented to an act. That is a matter of personal conscience, known only to God and to the person.

Given this, yes, it is still considered a grave matter to miss Sunday Mass, but it is not quite as simple as saying that it is always a mortal sin.

(Father Thom Hennen serves as the pastor of Sacred Heart Cathedral in Davenport. Send questions to

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