when is lying a mortal sin?

I have referred to the Catechism but I still don’t understand situations when lying can become a mortal sin. Is it basically as such: when someone doesn’t have the right to know the truth then lying would be a venial sin?

When you break the Commandment not to bear false witness. Think jury trial and lying then. Or more likely, lying at work to ruin the reputation of someone, perhaps causing them to be fired and their family’s future is ruined as well. It happens. Or you witness an accident and lie about it to the insurance company. How about this double header, two mortal sins for the price of one, lying on the tax forms the IRS sends to you home once a year. You’re stealing as well as lying mortally.

Does this help?

Glenda

Lying or any other sin is a mortal sin when it meets ALL of these three conditions:

  1. It must be a SERIOUS MATTER.

  2. Before the Sin, a person must have been mindful of the serious wrong, having reflected on the gravity of the situation, with SUFFICIENT REFLECTION, beforehand.

  3. A person must have freely chosen to commit the Sin, with the full consent of the FREE WILL.

The above answer concerns actual mortal sin, an objectively grave act that is committed with full knowledge of its grave immorality and full deliberation.

Which lies are objectively grave matter? (objective mortal sins)

Any lie told with a gravely immoral intention, such as malice or hatred.
Any lie whose object (moral object) is gravely disordered, such as lying under oath.
Any lie whose circumstances are such that the bad consequences of the lie gravely outweigh any good consequences.

The three fonts of morality (intention, moral object, circumstances) determine the objective morality of any act.

Thank you!

Whatever the case may be, deliberate venial sin is no small matter. I strongly encourage anyone who lies to break this sinful behavior.

It prevents us to a large degree from growing closer to God. Feel free to speak up and disagree if you think I am incorrect.

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Catechism:

2483 Lying is the most direct offense against the truth. To lie is to speak or act against the truth in order to lead someone into error. By injuring man’s relation to truth and to his neighbor, a lie offends against the fundamental relation of man and of his word to the Lord.

2484 The gravity of a lie is measured against the nature of the truth it deforms, the circumstances, the intentions of the one who lies, and the harm suffered by its victims. If a lie in itself only constitutes a venial sin, it becomes mortal when it does grave injury to the virtues of justice and charity.

2485 By its very nature, lying is to be condemned. It is a profanation of speech, whereas the purpose of speech is to communicate known truth to others. The deliberate intention of leading a neighbor into error by saying things contrary to the truth constitutes a failure in justice and charity. The culpability is greater when the intention of deceiving entails the risk of deadly consequences for those who are led astray.

scborromeo.org/ccc/p3s2c2a8.htm#2483 (more there).

Mental reservation is acceptable, however, in some tricky situations.

Not everyone has a right to know the truth. Mental reservation can take a number of different forms.

The first of which is to say nothing at all if questioned on something.

Let’s use the classic example: lying to a murderer to save the life of a friend. The intention and circumstances are both good. Would it still be classified as a gravely disordered moral object and therefore an objective mortal sin?

That type of lie would be objectively a venial sin. Intention and circumstances are good, and the moral object is not gravely disordered. But since “2485 By its very nature, lying is to be condemned.” we cannot justify any lie; it must always be at least a venial sin.

Saint Thomas in the Summa:
“It is written (Sirach 7:14): “Be not willing to make any manner of lie.””
“every lie is a sin, as also Augustine declares (Contra Mend. i).”
newadvent.org/summa/3110.htm#article3

That’s what I don’t understand. How do we determine if the moral object of a lie is gravely disordered?

Catechism:

2483 Lying is the most direct offense against the truth. To lie is to speak or act against the truth in order to lead someone into error. By injuring man’s relation to truth and to his neighbor, a lie offends against the fundamental relation of man and of his word to the Lord.

2484 The gravity of a lie is measured against the nature of the truth it deforms, the circumstances, the intentions of the one who lies, and the harm suffered by its victims. If a lie in itself only constitutes a venial sin, it becomes mortal when it does grave injury to the virtues of justice and charity.

2485 By its very nature, lying is to be condemned. It is a profanation of speech, whereas the purpose of speech is to communicate known truth to others. The deliberate intention of leading a neighbor into error by saying things contrary to the truth constitutes a failure in justice and charity. The culpability is greater when the intention of deceiving entails the risk of deadly consequences for those who are led astray.

scborromeo.org/ccc/p3s2c2a8.htm#2483 (more there).


Also a good example is a person who lies under oath in court.

2152 A person commits perjury when he makes a promise under oath with no intention of keeping it, or when after promising on oath he does not keep it. Perjury is a grave lack of respect for the Lord of all speech. Pledging oneself by oath to commit an evil deed is contrary to the holiness of the divine name.

Any of the three fonts of morality (intention, moral object, circumstances) is gravely disordered if it is incompatible with the love of God and the love of neighbor as self.

A venial sin is an act that is not so gravely immoral before God as to be entirely incompatible with true love of God and neighbor. An actual venial sin does not include sufficient culpability to take away the state of grace from the soul, nor to deserve eternal damnation. A venial sin is always in some way contrary to true love of God and neighbor, but to a substantially limited extent. An actual venial sin always includes some culpability and some lack of cooperation with grace, and always deserves some degree of punishment.

A mortal sin is an act that is so gravely immoral before God as to be entirely incompatible with true love of God and neighbor. An actual mortal sin includes sufficient culpability to take away the state of grace from the soul, and to deserve eternal damnation.

Saint Thomas Aquinas: “Therefore when the soul is so disordered by sin as to turn away from its last end, viz. God, to Whom it is united by charity, there is mortal sin; but when it is disordered without turning away from God, there is venial sin.” [Summa Theologica, I-II, Q. 72, A. 5.]

Pope John Paul II: “And when through sin, the soul commits a disorder that reaches the point of turning away from its ultimate end, God, to which it is bound by charity, then the sin is mortal; on the other hand, whenever the disorder does not reach the point of a turning away from God, the sin is venial. For this reason venial sin does not deprive the sinner of sanctifying grace, friendship with God, charity and therefore eternal happiness, whereas just such a deprivation is precisely the consequence of mortal sin.” [Reconciliation and Penance, n. 17]

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