Is foul or filthy language a sin?

And as a similar rule holds with regard to hearing and seeing in the case of what is obscene, the divine Instructor, following the same course with both, arrays those children who are engaged in the struggle in words of modesty, as ear-guards, so that the pulsation of fornication may not penetrate to the bruising of the soul; and He directs the eyes to the sight of what is honourable, saying that it is better to make a slip with the feet than with the eyes. This filthy speaking the apostle beats off, saying, “Let no corrupt communication proceed out of your mouth, but what is good.” And again, “As becometh saints, let not filthiness be named among you, nor foolish talking, nor jesting, which things are not seemly, but rather giving of thanks.” And if “he that calls his brother a fool be in danger of the judgment,” what shall we pronounce regarding him who speaks what is foolish?

Clement of Alexandria, The Instructor 2.6

From shameful things addressed to the ears, and words and sights, we must entirely abstain. And much more must we keep pure from shameful deeds: on the one hand, from exhibiting and exposing parts of the body which we ought not; and on the other, from beholding what is forbidden.

Clement of Alexandria, The Instructor 2.6

Now we exhort you, brethren and fellow-servants, to avoid vain talk and obscene discourses, and jestings, drunkenness, lasciviousness, luxury, unbounded passions, with foolish discourses, since we do not permit you so much as on the Lord’s days, which are days of joy, to speak or act anything unseemly; for the Scripture somewhere says: “Serve the Lord with fear, and rejoice unto Him with trembling.” Even your very rejoicings therefore ought to be done with fear and trembling: for a Christian who is faithful ought neither to repeat an heathen hymn nor an obscene song, because he will be obliged by that hymn to make mention of the idolatrous names of demons; and instead of the Holy Spirit, the wicked one will enter into him.

Anonymous (ANF), Constitutions of the Holy Apostles 6.2

As to unclean and light-minded talk, S. Paul says such things should not even be named Eph. v. 3. among us, for, as he elsewhere tells us, “Evil communications corrupt good manners.”

Francis de Sales, Introduction to the Devout Life 3.27

The apostle not only cautions against the gross acts of sin, but against what some may be apt to make light of, and think to be excusable. Neither filthiness ( v. 4 ), by which may be understood all wanton and unseemly gestures and behaviour; nor foolish talking, obscene and lewd discourse, or, more generally, such vain discourse as betrays much folly and indiscretion, and is far from edifying the hearers; nor jesting.

Matthew Henry, Commentary on Ephesians 5.2

For the only thing that is in reality shameful is wickedness, and what is done through it. In accordance with these remarks, conversation about deeds of wickedness is appropriately termed filthy [shameful] speaking, as talk about adultery and pæderasty and the like.

Clement of Alexandria, The Instructor 2.6

No filthy speech. He first forbids believers to use any filthy language, including under this name all those expressions which are wont to be employed for the purpose of inflaming lust. Not satisfied with the removal of the vice, he enjoins them to frame their discourse for edification.

John Calvin, Commentary on Galatians and Ephesians Ephesians 4.8

There is another vice of the Tongue which I cannot but mention, though I knew not in which of the former Classes to place it: not that it comes under none, but that tis so common to all, that tis not easy to resolve to which peculiarly to assign it, I mean obscene, and immodest talk, which is offensive to the purity of God, damageable and infectious to the innocence of our Neighbors, and most pernicious to ourselves: and yet is now grown a thing so common, that one would think we were fallen into an Age of Metamorphosis, and that the Brutes did (not only Poetically and in fiction) but really speak. For the talk of many is so bestial, that it seems to be but the conceptions of the more libidinous Animals clothed in human Language.

Richard Allestree, The Government of the Tongue 13

αισχρολογιαν, an old word for low and obscene speech which occurs here only in the N.T. It is made from αισχρολογος (αισχρος as in 1Co 11:6 and that from αισχος, disgrace). … Such language should never come out of the mouth of a Christian living the new life in Christ.

A.T. Robertson, Word Pictures in the New Testament 13.3

Wilt thou then learn how great an evil is filthy talking? See how the hearers blush at thy indecency. For what is viler than a filthy talker? what more infamous? … Better vent rottenness from the mouth than a filthy word.

John Chrysostom, Homilies on Second Corinthians 6

Truly, if each one shall give account for an idle word, how much more for words of impurity and shame? For words uttered hastily are far worse than idle words. If, therefore, an account is demanded for an idle word, how much more will punishment be exacted for impious language?

Ambrose of Milan, On the Duties of the Clergy 2.2

It is not food that defiles, but unjust disparagement of others and foul words. These things are openly shameful. In our office indeed must no word be let fall at all unseemly, nor one that may give offence to modesty.

Ambrose of Milan, On the Duties of the Clergy 2.18

For that the contrary conduct is troublesome, I mean the using filthy communication, is manifest from the fact that the soul is ashamed and blushes if it have been led to say any such thing and would not unless perhaps it were drunk. … So then thou dost it not, lest thou shouldest insult thy wife; and dost thou not blush at insulting God?

John Chrysostom, The Homilies of St. John Chrysostom on the Epistle to the Hebrews 17

First, on account of the very species of the acts employed for the purpose of fun, and this kind of jesting, according to Tully (De Offic. i, 29), is stated to be "discourteous, insolent, scandalous, and obscene," when to wit a man, for the purpose of jesting, employs indecent words or deeds, or such as are injurious to his neighbor, these being of themselves mortal sins. And thus it is evident that excessive play is a mortal sin.

Thomas Aquinas, Summa Theologica II-II.Q168.A3

By filthiness I understand all that is indecent or inconsistent with the modesty of the godly. By foolish talking I understand conversations that are either unprofitably or wickedly foolish; and as it frequently happens that idle talk is concealed under the garb of jesting or wit, he expressly mentions pleasantry, — which is so agreeable as to seem worthy of commendation, — and condemns it as a part of foolish talking The Greek word εὐτραπελία is often used by heathen writers, in a good sense, for that ready and ingenious pleasantry in which able and intelligent men may properly indulge. But as it is exceedingly difficult to be witty without becoming satirical, and as jesting itself carries in it a portion of conceit not at all in keeping with the character of a godly man, Paul very properly dissuades from this practice.

John Calvin, Commentary on Galatians and Ephesians Ephesians 5.2

The eyes may be shut when thou wilt, and are shut in a moment, but the ears thou canst only with an effort close: thou must raise the hand and reach them, and if any one hold thy hand, they are kept open, nor canst thou close them against reviling, impure, or flattering, and seducing words. And when thou hearest any things thou oughtest not to hear, though thou do it not, dost thou not sin with the ear? for thou hearest something that is bad with pleasure?

Augustine of Hippo, Sermons on Selected Lessons of the New Testament 8

For tell me, art thou pleased at hearing men blaspheme? Dost thou not rather shudder, and stop thine ears? Surely I think thou dost. Why so? Because thou blasphemest not thyself. Just so do thou act with respect to filthy talking also; and if thou wouldest show us clearly, that thou hast no pleasure in filthy speaking, endure not so much as to hear them. For when wilt thou be able to become good, bred up as thou art with such sounds in thine ears? When wilt thou venture to undergo such labors as chastity requires, now that thou art falling gradually away through this laughter, these songs, and filthy words?

John Chrysostom, The Homilies of St. John Chrysostom 40

Cleanse also thine ears, so that they may not listen except to holy and true discourse, that they never admit into them obscene, or infamous, or worldly words, or tolerate any one detracting from another, on account of that which is written, “Hedge up thine ears with thorns, and do not listen to a wicked tongue, that you may have your part with him, of whom it is said, that he was righteous in hearing and seeing; i.e. he sinned neither with his eyes nor his ears.

Sulpitius Severus, The Doubtful Letters of Sulpitius Severus 2.10