Is it a sin to cuss / swear / curse?

The third commandment forbids the taking of God's name in vain. An oath invoking God's name is a most serious matter. Elijah made such an oath to Obadiah, “As the Lord of hosts lives, before whom I stand” (1 Kings 18:15), and that oath was kept. But men would dare to use God's name often when not even intending to keep their word, thus totally in vain, which is gross evil. We know that people today swear by God with no concern about what they are doing. In fact, the Lord Jesus goes further than the law, by telling us “do not swear at all” (Matt. 5:33-37). For man had been proven by the time the Lord Jesus came, to be so untrustworthy that his promises concerning what he would do in the future were of no value. It would be different to swear to the truth of something that has already taken place, when one knows the facts.

"Hear the word of the Lord," do you say; "why what has the Lord to say to me? Certainly I do swear a bit, but what harm is there in that? I think nothing of it." Ah, that is just why we want you to hear the word of the Lord: we want you distinctly to understand what God thinks about it. God who hears every oath you utter. God says, "There is no truth, nor mercy, nor knowledge of God, in the land. By swearing, and lying, and killing, and stealing, and committing adultery, they break out, and blood touches blood. Therefore shall the land mourn."

The third commandment forbids taking God's name in vain (v.11). This may be done seriously or flippantly. One may seriously swear by God that he will do a certain thing, and then not do it. People are so irresponsible that such things become commonplace to the point of then using God's name flippantly, so that they don't care how offensively they talk. But God is not mocked: He will execute judgment on all who are ungodly, not only for their ungodly deeds, but for "all the harsh things which ungodly sinners have spoken against Him" (Jude 15).

Notice how much the things mentioned in verses 8 and 9 have to do with our tongues, and consequently with our hearts which express themselves thereby. Sins of the tongue are terribly common even among Christians. We all know the kind of words that are provoked by anger, wrath and malice. Would any true believer blaspheme? Hardly, yet how very easily it is to fall into speaking of God and of divine things in a light and irreverent way. How easy too it is to utter unsavoury things with our lips, even if we do not go so far as "filthy communications." And what about lying? An Ananias or a Sapphira may still be found. And we may go further and assert that every one of us who possesses a sensitive conscience knows right well that it is no easy thing to stick to absolute and rigid truth in all our utterances.

In Ephesians 5:3-6 we have serious instructions about our Christian behavior and conversation. Making puns with the Word of God is a hateful and sinful habit. Slang expressions are most unbecoming in a Christian. Let your speech be always with grace, seasoned with salt (Col. 4:6).

Next, it is not our deeds only that have to be considered, but our words. "Let no corrupt communication proceed out of your mouth, but that which is good to the use of edifying, that it may minister grace to the hearers." (Ver. 29.) Worthless language is to be eschewed as one rejects good-for-nothing fruit; if it were on the tongue, let the unprofitable word proceed no farther. Unclean allusion we shall find specified and forbidden in the chapter following. Here I conceive the circle is more comprehensive. Many who would neither utter nor hear impure conversation may often have to bemoan the utterance and the sanction of unsavoury discourse. Better to be silent if there be not (such is the force) something good for needful edification. The need measures the service, and love builds up instead of puffing up as knowledge does. It is equally true that "in the multitude of words there wants not sin," and that "the lips of the righteous feed many;" they "know what is acceptable;" and those who hear are refreshed and blessed.

Nor does he confine his warning to unbridled licentiousness or the covetous desire of that which might gratify man, but extends it to unholiness of language too, whether openly shameful or under the veil of refinement — "and [no] filthiness, and foolish talking, and jesting, which are not convenient, but rather giving of thanks." (Ver. 4.) Here again, not merely the absence of what is indecorous in the Christian, but the positive side is brought in and the heart's reference to God's goodness, which breaks out in thanksgiving. "For this ye know, that no whoremonger, or unclean person, or covetous man, who is an idolator, has any inheritance in the kingdom of Christ and God." (Ver. 5.) It is most important to remember, that let sovereign grace do what it will, let it go out to the vilest, let it cleanse the most defiled, the moral ways of God remain inflexible. His nature does not change. He hates and never can tolerate iniquity. His love may find and has found a glorious solution of the difficulty in the cross of Christ; but God and sin never can walk or dwell together.

As sinning with the tongue is throughout denounced, so here in particular the lack of reverence. For though the oaths in question refer to the creature rather than to God, though they may affect care for His name by substituting other forms for His; who entitles men to adopt anything of the sort in daily intercourse? He is the Judge, Who has assured us that of every idle word that men speak they shall give account in the day that comes; "for by thy words thou shalt be justified, and by thy words thou shalt be condemned."

Indeed on the mount, in the great series of discourses of which the first Gospel gives the summary, the Lord had pronounced on the same wrong. "Again, ye have heard that it was said to those of old time, Thou shalt not perjure thyself, but shalt perform to Jehovah thy vows; but I say to thee, Swear not at all: neither by the heaven, for it is God's throne; nor by the earth, for it is the footstool of his feet; nor by Jerusalem, for it is the city of the great King. No more shalt thou swear by thy head; for thou canst not make one hair white or black. But let your word be yea, yea; nay, nay; for that which is more cometh of evil" (or, the evil one). The self-same duty is enforced as in this Epistle.

When a man swears, he allows this impatience of the heart to act; he forgets the glory and majesty of God, irreverently introducing His name with unbridled flesh to confirm an assertion, or to give force to a vow, or in His place he puts some creature whom he invests with the authority and power that belongs to God alone. The root of all is the unsubdued will and unbridled passions of man's heart. Only, with an intuitive sense of his impotency to ensure the fulfilment of his desires, he irreverently brings God in, or, as a heathen of old was wont to do, he introduces some creature practically deified for the occasion. It is not lust, but the unbridled impetuosity of the flesh (see Col. 3:8), the irreverence, presumption, and independence of the man carried to its utmost extent.

"Again ye heard that it was said to the ancients, Thou shalt not swear falsely, but shalt render to the Lord thine oaths. But I say to you, Swear not at all; neither by (in) the heaven, for it is God's throne; nor by the earth, for it is his feet's footstool; nor by (toward) Jerusalem, for it is the great King's city. Nor shalt thou swear by thy head, because thou canst not make one hair white or black. But let your word be, Yea, yea; Nay, nay; but what exceedeth these is of evil (or, the evil one)."

Thus the Lord goes far beyond perjury or breaking a vow. He prohibits swearing altogether in the intercourse of daily life. Our word therein is to be, Yea, yea, or Nay, nay. That which is more than these has no sanction from God, and is therefore of evil, or the evil one, the enemy of God and man. All such asseveration as the Lord illustrates from the facts of Jewish habit arose from the constant experience of men in deceiving or evading. They therefore resorted to such means of insuring the truth. But these efforts defeated themselves; for we know from a reliable Jewish contemporary of the N.T. inspired writers that oaths by earth, heaven, sun, stars, and the entire universe, were not counted binding. Only those obliged the conscience which were by God's name direct and express; nay others might be transgressed. As the Lord supposed in those He addresses poverty of spirit and purity of heart, He proscribed absolutely all such swearing as offensive to God and incompatible with the place of His sons.