Is it a mortal sin not to fast or abstain from meat during Lent?

Is it a mortal sin not to fast on Ash Wednesday or on Good Friday? Is it a mortal sin not to abstain from meat on a Friday of Lent?
Is it a mortal sin to miss Mass on a Sunday or on a holy day of obligation, without a just reason? These questions all have the same basic form. Is it a mortal sin to fail to do something required by the eternal moral law? The answer depends on whether the failure is full or limited.

Negative Precepts vs. Positive Precepts

There are two types of moral requirements: positive precepts and negative precepts. The negative precepts are the “Thou shalt nots”. They prohibit an act. You shall not steal. You shall not commit adultery. You shall not do this particular act, because its performance is a sin. The positive precepts require an act. You shall worship the Lord your God. You shall keep holy the Sabbath. You shall do this particular act, because its performance is required in order to avoid sin. Under the negative precepts, we sin if we do the act in question. Under the positive precepts, we sin if we do not do the act in question.

The requirements to fast, to abstain from meat, and to attend Mass all fall under the positive precepts. You shall do these acts, because to deliberately choose not to do these acts, without a just reason, is a sin.

Pope John Paul II: “The negative precepts of the natural law are universally valid. They oblige each and every individual, always and in every circumstance. It is a matter of prohibitions which forbid a given action semper et pro semper [always and in each instance], without exception, because the choice of this kind of behavior is in no case compatible with the goodness of the will of the acting person, with his vocation to life with God and to communion with his neighbor. It is prohibited — to everyone and in every case — to violate these precepts.” (Veritatis Splendor, n. 52).

If it is a sin to commit a particular act, then the act falls under the negative precepts. You are prohibited from committing that act at all times. It is possible to fulfill negative precepts continually because their fulfillment consists in choosing to refrain from acting. You can refrain from acting while you are awake or asleep, while you are busy or idle, etc.

If it is a sin to refuse to commit a particular act, then the act falls under the positive precepts. You must commit the act in question: worshipping God, honoring your parents, giving alms, etc. But while negative precepts can be fulfilled continually, positive precepts cannot. You cannot give alms continually, whether awake or asleep, at all times on all days. For example, you cannot do those particular acts, at all times, which fulfill the commandment to honor your parents. Therefore, the positive precepts allow for a prudential judgment as to when and how they will be fulfilled.

Jesus Christ: “How can the sons of the groom mourn, while the groom is still with them? But the days will arrive when the groom will be taken away from them. And then they shall fast.” (Mt 9:15)

Pope John Paul II: “In the case of the positive moral precepts, prudence always has the task of verifying that they apply in a specific situation, for example, in view of other duties which may be more important or urgent.” (Veritatis Splendor, n. 67)

Mortal Sin vs. Venial Sin

The violation of a negative precept can be a mortal sin or a venial sin. Adultery is always a mortal sin because it offends against a grave obligation (keeping the marital vows, and refraining from sex outside of marriage) to a grave extent. An offense against the marital vows to a substantially limited extent would be only a venial sin. For example, if a husband takes his wife out for dinner, and he flirts with the waitress, then he sins only venially.

Venial sins are substantially limited offenses against the eternal moral law. Mortal sins are substantially full offenses against the eternal moral law. A substantially limited offense against a grave obligation is a venial sin. It is not a mortal sin because a substantially limited offense against God is not sufficient to deprive a person of the state of grace, nor to deserve eternal punishment in Hell.

The violation of a positive precept can be a mortal sin or a venial sin. The continuous refusal to worship God is a mortal sin. Failing to worship God on a particular occasion is not a sin. The positive precepts cannot be fulfilled continuously, at least not in our fallen state in this life.

Keeping holy the Sabbath (which includes holy days of obligation as a type of Sabbath) is fulfilled in many different ways. If you only fulfill this positive precept by going to Mass, you have sinned. Keeping holy the Sabbath is a general obligation that includes refraining from unnecessary work, especially arduous labor, worshipping God in various ways, etc. So keeping holy the Sabbath is not equivalent to attending Mass.

The obligation to fast on Ash Wednesday and Good Friday, and to refrain from eating meat on Fridays of Lent, are part of the positive precept requiring us to practice self-denial.

Jesus Christ: “If anyone is willing to come after me: let him deny himself, and take up his cross every day, and follow me. For whoever will have saved his life, will lose it. Yet whoever will have lost his life for my sake, will save it.” (Lk 9:23-24)

The path to eternal life requires self-denial, which includes fasting, and abstaining from meat, at certain times. This obligation under the positive precepts is grave; deliberate failure, to a grave extent, to practice self-denial is a mortal sin. But it is only a mortal sin if the failure to fulfill the grave obligation is a grave failure.

{16:19} A certain man was wealthy, and he was clothed in purple and in fine linen. And he feasted splendidly every day.
{16:20} And there was a certain beggar, named Lazarus, who lay at his gate, covered with sores,
{16:21} wanting to be filled with the crumbs which were falling from the wealthy man’s table. But no one gave it to him. And even the dogs came and licked his sores.
{16:22} Then it happened that the beggar died, and he was carried by the Angels into the bosom of Abraham. Now the wealthy man also died, and he was entombed in Hell.

The wealthy man sinned gravely because he failed to fulfill grave positive precepts — fasting and self-denial, giving alms, and other positive expressions of the love of neighbor — to a grave extent. His deliberate failure was substantially full.

However, a substantially limited failure to fast or to abstain from meat or to give alms is not a grave sin. If you fail to put money in the collection basket at Mass on a particular occasion, even though you are able, it is not a grave sin. If you never give alms to the Church or to the needy, despite your ability to do so, then it is a grave sin.

(1) If you attend Mass regularly, but miss Mass on a Sunday or a holy day, without a just reason, on a particular occasion, it is a venial sin, not a mortal sin. You have failed to fulfill a positive precept, but only to a limited extent. See my article: Is it always a mortal sin to miss Mass?.

(2) If you have decided not to attend Mass any more, then you have committed a mortal sin.

The first case is only a venial sin because the person has fulfilled the positive precepts to worship God and to keep holy the Sabbath many times in many ways. The offense of missing Mass without a just reason is therefore a substantially limited failure against a grave obligation. To be a mortal sin, a sin must be a grave offense (a substantially full offense) against a grave obligation.

Do you really believe that Jesus Christ would send everyone to Hell, who misses Mass even once without a good reason, and who does not repent, though they have attended Mass regularly? Do you really believe that the Holy Spirit would refuse to dwell (by the state of grace) in all persons who eat meat on any one Friday of Lent, though they generally fast, abstain, and practice self-denial? If you think so, then you are sinning by accusing God of being merciless and unreasonable. If you think so, then you have fallen into the error of the Pharisees.

The failure to fast on a particular fast day, or the failure to abstain from meat on a particular day for abstaining, if it is done deliberately and without a good reason, is a sin. But it is not a mortal sin, if the person does fast and abstain and practice self-denial on many other occasions. An act that is a substantially limited offense against the love of God, and the love of neighbor as self, cannot be a mortal sin. No substantially limited offense deprives the individual of the state of grace. No substantially limited offense deserves eternal punishment in Hell.

As long as you generally fulfill the positive precepts to fast, to abstain from meat, and to practice self-denial, then a particular failure of that obligation, on a particular occasion, cannot be a mortal sin. For you have generally fulfilled what the positive precept requires of you, despite a substantially limited failure on occasion.

Ronald L. Conte Jr.
Roman Catholic moral theologian and
translator of the Catholic Public Domain Version of the Bible.

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