Understanding Mortal Sin

The following term is so provocative, disturbing, and shocking – it is so unsettling and divisive – that sensitive adults should brace themselves. Don’t worry about the children. They get it.

Mortal sin.

Kids know that some sins are seriously evil, even unspeakably immoral. Adults (including priests, bishops, and popes), on the other hand, have had many years to rationalize mortal sin, usually categorized under the banner of non-judgmentalism, diversity, equity, and inclusion. So they give the impression that right and wrong are cultural.

Religious maturity – so the argument goes – means considering it better to assess our general direction in the spiritual life. Do we comply with cultural expectations? Did we violate any mandates? The concept of the intrinsic evil of mortal sin – again, the argument goes – is too simplistic in a complex, technological world. One sin isn’t sufficient to derail our standing with God, is it?

But Catholic moral theology teaches that one grave violation of God’s law that goes without repentance has eternal consequences.

Saint Thomas teaches that law is an ordinance of right reason, promulgated by a competent authority, for the sake of the common good. Some add “enforceable” as a defining element. Traffic laws usually fit the definition. Municipal fire and safety codes are commonly reasonable, authoritative, and just. Tax laws passed by Congress and signed by the president are, broadly speaking in theory, necessary to fund government operations.

Authorities can distort and degrade otherwise just laws. Municipal ordinances can be excessive, and politicians can use tax laws for social and economic manipulation. The tax code has become so complicated and confusing that we need experts to decipher it. At what point do tax laws become unjust? In 1453, the Byzantine Empire fell to Muslims. The obligatory tax required by the Muslim invaders (zakat) wasn’t as burdensome as the complicated Byzantine taxes. Most of us do not know when we violate modern tax laws.

The laws that derive from Roe v. Wade are unjust because they violate reason and the common good. Bad law has consequences. The tortuous logic that justifies modern child sacrifice has damaged the cultural understanding of the rules of logic. An entire nation seems unable to reason well. Witness this judicial catechism lesson by Justice Anthony Kennedy that reaffirmed Roe in Planned Parenthood v. Casey (1992): “At the heart of liberty is the right to define one’s own concept of existence, of meaning, of the universe, and of the mystery of human life.”

So today, by law, we can “self-identify” as we please, and we do.


As we define our own concept of existence, grotesque surgical mutilations – approved by the government and paid by insurance plans – are no longer “crimes against humanity.” They have become part of the “mystery of life” with breathtaking self-deception. So the first “female” admiral in the U.S. Public Health Service Commissioned Corps’ history is a man disguised as a woman. Without faith and reason – and the rigors of logic – we lose our minds.

God’s law is the perfect remedy. The Ten Commandments are ordinances of right reason, promulgated by the eternally competent Authority, serving the common good. God’s laws are inescapable and enforceable from eternity.

Jesus teaches us that the love of God and neighbor encapsulates God’s law. The first three of the Ten Commandments teach us how to love God. The following seven teach us now to love our neighbor. The Commandments are just, reasonable, and accessible. Society is much better off as a “Ten Commandment Society” that worships God, honors parents and lawful authorities, respects human life and sexuality, remains faithful in marriage, respects property rights, and speaks honestly.

Deliberate violations of the Commandments – with knowledge and assent – are sins. A mortal sin is an offense against the law of God with these components: grievous matter, sufficient reflection, and full consent of the will. Examples include blasphemy, insufficient reasons for missing Mass, hatreds, murder, mutilation, abuse of human sexuality, theft, shoplifting, calumny, etc. “Sufficient reflection” means that we must know that the thought, word, or deed is sinful at the time we commit it; and “full consent of the will” means that we fully and willfully yielded to the action. A single mortal sin ruptures our relationship with God.

What is the result of mortal sin?

Here is another term that is provocative, disturbing, and shocking. It is so unsettling and eternally divisive that sensitive adults should again beware. Again, don’t worry about the children. (They expect God’s justice because they’re innocent. Adults count on God’s mercy because we’re not.)

Eternal damnation.

The Church teaches that a single mortal sin deprives us of sanctifying grace and – without repentance – brings everlasting death and damnation to the soul. The Roman Canon during Mass begs God to “save us from final damnation.” Nevertheless, adults are afraid to use the term. Even priests, bishops, and popes are uncomfortable with it. It’s so. . .so irretrievably definitive. But kids know the prospect of eternal damnation is perfectly reasonable. Even kids who have never attended Catholic school believe in Hell.

Need evidence? Halloween. Zombie movies. Horror films. “They’re coming to get you, Barbara.” These films tap into a subliminal awareness: Alive yet not alive – suffering in horror and disgrace for eternity. Here’s the escape clause for the kids. The movies come to an end, even if the monster survives to appear again in a sequel. But Hell is eternal, the consequence of rejecting God with a single action and dying in the state of mortal sin. Defining “one’s own concept of existence” comes at a terrible price.

The Church has a remedy for mortal sin and its chilling prospect. The leaves are falling. We are preparing for winter. Liturgically, we are also preparing for the end of our lives. November is the month of the Last Things, death, judgment, Heaven, and Hell.

So repent and believe in the Gospel, and check the Confession schedule.


*Image: The “Mouth of Hell” from The Hours of Catherine of Cleves by the Master of Catherine of Cleves, c. 1440 [Morgan Library, New York, NY]



Father Jerry J. Pokorsky is a priest of the Diocese of Arlington. He is pastor of St. Catherine of Siena parish in Great Falls, Virginia.