The Second Commandment
"Thou shalt not take the Name of the Lord thy God in vain"
COMPENDIUM
This Commandment forbids: 1. uttering the Name of God without respect; 2. blaspheming or speaking ill of God, the Blessed Virgin, or the Saints; 3. making false or unnecessary oaths, or swearing in any unlawful way.
Uttering the Name of God without respect is to pronounce His Holy Name or to speak of anything which has some particular connection with God, as, for instance, the Name of Jesus, or of Mary, or of the Saints, in anger or in jest, or in any other irreverent manner. Both blasphemy and imprecation are forbidden by this Commandment. The difference between them is this: blasphemy is cursing or wishing ill to God or our Lady or the Saints, whereas imprecation is cursing or wishing ill to oneself or one's neighbor.
Making an oath or swearing is calling God as witness of anything which is affirmed or promised. Swearing is not always forbidden; it is lawful and honorable to God when it is done under necessity, and if the oath is taken with truth, sound judgment and justice. Truth is wanting if anyone affirms with an oath what he knows or believes to be false, and when he promises in this way to do something which he has no intention of performing. Good judgment and prudence are wanting if the oath be taken without due consideration or for things of no importance. Lastly, justice is wanting when anyone swears to do something unlawful or wrong, as, for instance, to take revenge, rob or steal, or the like. In such cases, not only are we not obliged to keep such oaths, but it would be a sin to keep them, because the acts are forbidden by the Law of God or of the Church. He who swears falsely commits a mortal sin, because he gravely dishonors God, who is infinite truth, by calling Him as witness to what is false.
The Second Commandment orders us to honor the Holy Name of God, and, besides this, to fulfill our oaths and vows. By a vow is meant a promise made to God of something which is good and within our power and better than its opposite, and it binds the maker of the vow as if it were a command. The Bishop of the diocese or the Supreme Pontiff may be asked to commute or dispense from a vow, according to the nature of the vow. The transgression of a vow is a sin, and, therefore, vows should not be made without ripe reflection, nor, ordinarily, without consulting a confessor or some other prudent person, so as to avoid any risk of incurring the danger of sinning. Vows can only be made to God, and not to our Lady or the Saints; but they can be promised to God in honor of our Lady and the Saints.
CATECHISM
372. What does the Second Commandment: Thou shalt not take the Name of the Lord thy God in vain, forbid?
The Second Commandment: Thou shalt not take the Name of the Lord thy God in vain, forbids us: 1. to utter the Name of God irreverently; 2. to blaspheme God, the Blessed Virgin or the Saints; 3. to take false, unnecessary, or unlawful oaths.
373. What is meant by: to utter the Name of God irreverently?
To utter the Name of God irreverently means to mention this Holy Name, or any other name that in a special way refers to God Himself, such as the name of Jesus, of Mary and the Saints, in anger or in jest or in any irreverent way whatsoever.
374. What is blasphemy?
Blasphemy is a horrible sin which consists in words or acts of contempt or malediction against God, the Blessed Virgin, the Saints, or sacred things.
375. Is there any difference between blasphemy and imprecation?
There is a difference, because by blasphemy one wishes evil to or curses God, the Blessed Virgin or the Saints; while by imprecation, one wishes evil to or curses one's self or one's neighbor.
376. What is an oath?
An oath is the calling on God to witness the truth of what one says or promises.
377. Is it always forbidden to take an oath?
It is not always forbidden to take an oath; an oath is lawful and even gives honor to God, when it is necessary, and when one swears with truth, judgement and justice.
378. When is an oath without truth?
An oath is without truth when one affirms on oath what he knows or believes to be false, or when one promises under oath to do what one has no intention of doing.
379. When is an oath without judgement?
An oath is without judgment when one makes oaths imprudently and without mature consideration, or in trivial matters.
380. When is an oath without justice?
An oath is without justice when one makes an oath to do something unjust or unlawful, as, for example, to swear to take revenge, or to steal, and so on.
381. Are we obliged to keep an oath to do unjust or unlawful things?
Not only are we not obliged, but we should sin by doing such things, because they are forbidden by the Laws of God and of the Church.
382. What sin does he commit who swears falsely?
He who swears falsely commits a mortal sin, because he grievously dishonors God, the Infinite Truth, by calling Him to witness what is false.
383. What does the Second Commandment command us to do?
The Second Commandment commands us to honor the Holy Name of God as well as to keep our oaths and vows.
384. What is a vow?
A vow is a promise made to God regarding something which is good, within our power, and better than its opposite, and to the keeping of which we bind ourselves just as if it had been commanded us.
385. If the keeping of a vow were to become very difficult, in whole or in part, what is to be done?
Commutation or dispensation may be sought from one's Bishop or from the Pope, according to the character of the vow.
386. Is it a sin to break a vow?
It is a sin to break a vow and, therefore, we should not make vows without mature reflection, nor, as a rule, without the advice of our confessor or other prudent person, so as not to expose ourselves to the danger of sinning.
387. May vows be made to our Lady and the Saints?
Vows are made to God alone; we may, however, promise God to do something in honor of our Lady or the Saints.