Is Betrayal Limited to a Sin of Commission?

Is the intentional betrayal of another person always a sin of commission? Or, are there instances in which the betrayal of another is relegated a sin of omission?

Any thorough examination of these questions, should begin with a proper definition of betrayal:

the act of exposing or delivering someone to an enemy through treachery or disloyalty; the act of disappointing a person’s trust, hopes, or expectations; the act of revealing information in violation of confidence; failure to keep or honor a promise, principle, cherished memory; an act or instance of unconsciously revealing or displaying some quality or characteristic, typically one preferably concealed.[1]

In considering this definition, what immediately comes to light, is the fact that one would normally share a particular relationship with the other, a level of intimacy that enables gravity in betraying the other. This could fall into the category of friendship, spousal relationship, or that of relatives and acquaintances etc. And, the fact that, the covenantal bond with one’s spouse, or the bond with one’s relatives, forms a loving relationship between persons, a special relationship that demands honor, trust and loyalty. To betray one such as this, would be an especially grievous offense.

Toward this end, the Book of Sirach cautions and guides one in the selection of friends:

Pleasant speech multiplies friends, and gracious lips, friendly greetings. Let those who are friendly to you be many, but one in a thousand your confidant. When you gain friends, gain them through testing, and do not be quick to trust them. For there are friends when it suits them, but they will not be around in time of trouble. Another is a friend who turns into an enemy, and tells of the quarrel to your disgrace. Others are friends, table companions, but they cannot be found in time of affliction. When things go well, they are your other self, and lord it over your servants. If disaster comes upon you, they turn against you and hide themselves. Stay away from your enemies, and be on guard with your friends. Faithful friends are a sturdy shelter; whoever finds one finds a treasure. Faithful friends are beyond price; no amount can balance their worth. Faithful friends are life-saving medicine; those who fear God will find them. Those who fear the Lord enjoy stable friendship, for as they are, so will their neighbors be.[2]

Here, one receives both warning and guidance. That, it is he, or she, who is pleasant and gracious in speech, who will multiply friends and receive friendly greetings. That, although many may show themselves to be friendly, only one in a thousand should be chosen as a true confidant. That, when one gains friends, one should gain them through testing; a friend must be tested before one’s trust be given over completely. That, another may be a friend who turns into an enemy, for there are many who are friends when it suits them, but they will not be around in time of trouble. That, it is he who finds a true and faithful friend, who finds a treasure, he, or she, is beyond price and a life-saving medicine.

But, why is a faithful friend considered a treasure? Why is he, or she, beyond price and a life-saving medicine? It is because a true friend, spouse, relative or acquaintance – through the grace of God – loves, honors, trusts and is loyal to his, or her, friend. He, or she, does not seek to intentionally harm their friend, spouse, relative or acquaintance, through betraying them.

Thus, the sin of betrayal, can be both mortal or venial:

For a sin to be mortal, three conditions must together be met: “Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent” (cf. RP 17§12).

Grave matter is specified by the Ten Commandments, corresponding to the answer of Jesus to the rich young man: “Do not kill, Do not commit adultery, Do not steal, Do not bear false witness, Do not defraud, Honor your father and your mother” (cf. Mk 10:19). The gravity of sins is more or less great: murder is graver than theft. One must also take into account who is wronged: violence against parents is in itself graver than violence against a stranger.

…It presupposes knowledge of the sinful character of the act, of its opposition to God’s law. It also implies a consent sufficiently deliberate to be a personal choice. Feigned ignorance and hardness of heart (cf. Mk 3:5-6; Lk 16:19-31) do not diminish, but rather increase, the voluntary character of a sin.

Unintentional ignorance can diminish or even remove the imputability of a grave offense. But no one is deemed to be ignorant of the principles of the moral law, which are written in the conscience of every man. The promptings of feelings and passions can also diminish the voluntary and free character of the offense, as can external pressures or pathological disorders. Sin committed through malice, by deliberate choice of evil, is the gravest.[3]

To be mortal, there must be a sin whose object is grave matter: When the will sets itself upon something that is of its nature incompatible with the charity that orients man toward his ultimate end, then the sin is mortal by its very object . . . whether it contradicts the love of God, such as blasphemy or perjury, or the love of neighbor, such as homicide or adultery….[4]

When the will sets itself upon something, that is by its very nature incompatible with the charity that orients man toward Eternal life (grave matter: blasphemy, perjury, homicide and adultery) one’s intention is to commit mortal sin. But, to be mortal, it must also be committed with full knowledge, (true understanding) that (blasphemy, perjury, homicide and adultery) are grave matter, and fully cognizant of this, go forward with deliberate consent to commit this act.     

To be venial, the sin of betrayal would need to be a minor breach of trust, loyalty or confidence, which lacks grave matter or full knowledge – such as a lesser unfaithfulness or broken promise.

And, just as the sin of betrayal can be mortal or venial, it can also be a sin of commission or omission. While a sin of commission, is a chosen act that positively violates or goes against God’s commands. A sin of omission is defined as:[w]illful neglect or positive refusal to perform some good action that one’s conscience urges one to do. Such omission is morally culpable, and its gravity depends on the importance of what should have been done, on the person’s willfulness, and the circumstances of the situation.[5]

Thus, due to the nature of one’s relationship, the betrayal of a casual acquaintance, is less in gravity than that of a spouse. One is not in a sacramental or marital bond with a casual acquaintance. And, if one fully understands adultery to be grave matter, and chooses to give one’s deliberate consent to relations with someone other than one’s spouse, one commits mortal sin.

One can also betray another through a mortal sin of omission. For example, if one were to come to knowledge that one’s daughter was considering abortion, and he, or she, chooses a course of inaction that allows the daughter to go through with the abortion unhindered, he, or she, commits a sin of omission. And, if one fully understands abortion to be grave matter, and nevertheless, chooses to give one’s deliberate consent to a course of inaction – it is a mortal sin of omission. Not to mention, a clear betrayal on multiple levels: a parental betrayal, through one’s withholding the truth, assistance and support one’s daughter requires; a moral betrayal, by not standing up for justice and the vulnerable unborn child; and a spiritual betrayal, by not sharing one’s faith, when one clearly has the opportunity and duty to do so.

Does it not stand to reason then – that if one strives to be virtuous through the grace of God – avoiding sin and the betrayal of persons – one is striving to avoid the betrayal of Christ?

‘Come, you who are blessed by my Father. Inherit the kingdom prepared for you from the foundation of the world. For I was hungry and you gave me food, I was thirsty and you gave me drink, a stranger and you welcomed me, naked and you clothed me, ill and you cared for me, in prison and you visited me.’ Then the righteous will answer him and say, ‘Lord, when did we see you hungry and feed you, or thirsty and give you drink? When did we see you a stranger and welcome you, or naked and clothe you? When did we see you ill or in prison, and visit you?’ And the king will say to them in reply, ‘Amen, I say to you, whatever you did for one of these least brothers of mine, you did for me.’[6]

Therefore, out of love for God, should not a faithful Christian come to the understanding that:

In her Magisterial teaching of the faith and in the witness of her saints, the Church has never forgotten that “sinners were the authors and the ministers of all the sufferings that the divine Redeemer endured” (cf. Roman Catechism I,5, 11; cf. Heb 12:3).Taking into account the fact that our sins affect Christ himself (cf. Mat 25:45; Acts 9:4-5), the Church does not hesitate to impute to Christians the gravest responsibility for the torments inflicted upon Jesus, a responsibility with which they have all too often burdened the Jews alone: We must regard as guilty all those who continue to relapse into their sins. Since our sins made the Lord Christ suffer the torment of the cross, those who plunge themselves into disorders and crimes crucify the Son of God anew in their hearts (for he is in them) and hold him up to contempt. And it can be seen that our crime in this case is greater in us than in the Jews. As for them, according to the witness of the Apostle, “None of the rulers of this age understood this; for if they had, they would not have crucified the Lord of glory.” We, however, profess to know him. And when we deny him by our deeds, we in some way seem to lay violent hands on him (cf. Roman Catechism I,5, 11; cf. Heb 6:6; 1 Cor 2:8).[7]

This being so:

Do your own part also, with great eagerness and determination. “And the things that you have heard of me among many witnesses, the same commit thou to faithful men.” That is, to faithful men, not to those who raise questions or argue, but to faithful men. How faithful? They must be the kind who do not betray the Gospel they are to preach. …And he does not say, Tell them, but, Commit them. For when a treasure is committed to someone, it is placed in safe keeping. Again, he warns his disciple by things above and things below. But he does not say only, commit them to faithful men. For what use is it if a man is faithful, if he is not able to pass his teaching on to others? What if he does not betray the faith, but also does not make others faithful? Therefore, the teacher must have two qualities: he must be faithful and able to teach. That is why he says, “who shall be able to teach others also.”[8]

[1] Dictionary.com. s.v. “betrayal”. accessed August 10, 2026. https://www.dictionary.com/browse/betrayal

[2] Confraternity of Christian Doctrine, Catholic Church, Saint Joseph Edition of the New American Bible (Washington, D.C. United States Conference of Catholic Bishops, and Totowa, NJ: Catholic Book Publishing Co. 2011)., Sir 6:5-17., (Hereafter cited as NAB).

[3] Catholic Church. Catechism of the Catholic Church: Revised in Accordance with the Official Latin Text Promulgated by Pope John Paul II, 2nd ed. (Vatican City; Washington, DC: Libreria Editrice Vaticana; United States Catholic Conference, 1997), 1857-1860. (hereafter cited as CCC)

[4] Ibid., 1856.

[5] Catholicculture.org. s.v. “omission”. accessed August 9, 2026. https://www.catholicculture.org/culture/library/dictionary/index.cfm?id=35258&randomterm=false

[6] NAB, Mat 25:34-40.

[7] CCC, 598.

[8] TheHistoricFaith.com. St. John Chrysostom. Homilies on Second Timothy. Homily 4. P2. accessed August 9, 2026.   https://thehistoricfaith.com/en/library/john-chrysostom/john-chrysostom/homilies-on-second-timothy