The following is an excerpt from The MacArthur New Testament Commentary on Ephesians 5.

But do not let immorality or any impurity or greed even be named among you, as is proper among saints; and there must be no filthiness and silly talk, or coarse jesting, which are not fitting, but rather giving of thanks. (5:3–4)Whatever God establishes, Satan will counterfeit. Where God establishes true love, Satan produces counterfeit love. Counterfeit love characterizes Satan’s children, those who are of the world, just as true love characterizes God’s children, those who are citizens of heaven.

In contrast to godly, unselfish, forgiving love, the world’s love is lustful and self–indulgent. It loves because the object of love is attractive, enjoyable, pleasant, satisfying, appreciative, loves in return, produces desired feelings, or is likely to repay in some way. It is always based on the other person’s fulfilling one’s own needs and desires and meeting one’s own expectations. Worldly love is reciprocal, giving little in the expectation of getting much. Speaking of that kind of love, Jesus said, “For if you love those who love you, what reward have you? Do not even the tax–gatherers do the same?” (Matt. 5:46).

The world claims to want love, and love is advocated and praised from every corner. Romantic love especially is touted. Songs, novels, movies, and television serials continually exploit emotional, lustful desire as if it were genuine love. Questing for and fantasizing about the “perfect love” is portrayed as the ultimate human experience.

It should not be surprising that the misguided quest for that kind of love leads inevitably to immorality and impurity, because that kind of love is selfish and destructive, a deceptive counterfeit of God’s love. It is always conditional and is always self–centered. It is not concerned about commitment but only satisfaction; it is not concerned about giving but only getting. It has no basis for permanence because its purpose is to use and to exploit rather than to serve and to help. It lasts until the one loved no longer satisfies or until he or she disappears for someone else.

Porneia (immorality) refers to all sexual sin, and all sexual sin is against God and against godly love. It is the antonym of enkrateia, which refers to self–control, especially in the area of sex. When Paul spoke before Felix and his wife Drusilla, “discussing righteousness, self–control and the judgment to come, Felix became frightened and said, ‘Go away for the present, and when I find time, I will summon you’ ” (Acts 24:24–25). Felix had stolen Drusilla from her former husband and was therefore living with her in an adulterous relationship. The sexual self–control of which Paul spoke pertained to lustful passion, as Felix understood. The message to the governor was that he was living contrary to God’s righteousness by refusing to discipline his sexual desire, and for that he was subject to God’s judgment.

Loss of sexual self–control leads to its opposite, which is immorality and impurity. Akatharsia (impurity) is a more general term than porneia, referring to anything that is unclean and filthy. Jesus used the word to describe the rottenness of decaying bodies in a tomb (Matt. 23:27). The other ten times the word is used in the New Testament it is associated with sexual sin. It refers to immoral thoughts, passions, ideas, fantasies, and every other form of sexual corruption.

Contemporary sex madness has even found its way into the church. The influence of the lustful world has been so pervasive and the church so weak and undiscerning that many Christians have become convinced that all sorts of sexual excesses and impurities are covered by grace or can be rendered morally safe if engaged in with the right attitude—especially if some Scripture verse can be twisted to give seeming support. But immorality and impurity cannot be sanctified or modified into anything better than what they are, which is wickedness—a crime against the holy God and the loving Savior. In 1 Corinthians 5:1–5 and 6:13–20 Paul shows that there is no place for that in the Christian life.

As mentioned under the discussion of Ephesians 4:19, greed is inseparable from impurity. Every form of sexual immorality is an expression of the self–will, self–gratification, and self–centeredness of greed. It is by nature contrary to love, which is self–giving. Immorality and impurity are but forms of greed in the realm of sexual sin. They are manifestations of sexual covetousness and express counterfeit love (which is really hate, since love seeks the purity of others and is unselfish), masquerading as something beautiful, good, and rewarding. Because those sins seem so attractive and promising, spouses are forsaken, children are neglected, homes are destroyed, friends are disregarded, as no effort is spared to fulfill the desire to have the one who is lusted after—all of that in the name of love.

Because of the strong sexual nature of human beings, sexual sins are powerful and can become perverted in unimaginable ways. If given free rein, sexual sins lead to complete insensitivity to the feelings and welfare of others, to horrible brutality, and frequently to murder—as news stories testify daily.

That is why the sins of immorality or any impurity or greed should not even be named among Christians, as is proper among saints. Those sins cannot in any way be justified, and they should not in any way be tolerated. The meaning of saints is “holy ones,” and those who are holy have nothing to do with that which is unholy.

Paul continues his warning against this perversion of love by mentioning an extensive list of related sins that is sure to cover every believer at one time or another. Not only should Christians never engage in sexual sins of any kind, but they should never be guilty of filthiness and silly talk, or coarse jesting.

Filthiness has to do with general obscenity, any talk that is degrading and disgraceful. It comes from the same Greek root as “disgraceful” in verse 12, where Paul says that such vile things should not even be mentioned, much less participated in, and is related to the term in Colossians 3:8, meaning “dirty speech.”
Morologia (silly talk) used only here in the New Testament, is derived from moros (which means dull, or stupid, and is the word from which we get moron) and lego (to speak). It is stupid talk, talk only befitting someone who is intellectually deficient. It is sometimes referred to as low obscenity, foolish talk that comes from the drunk or the gutter mouth. It has no point except to give an air of dirty worldliness.

Eutrapelia (coarse jesting), on the other hand, refers to talk that is more pointed and determined. It carries the idea of quickly turning something that is said or done—no matter how innocent—into that which is obscene or suggestive. It is the filthy talk of a person who uses every word and circumstance to display his immoral wit. It is the stock–in–trade of the clever talk–show host who is never at a loss for sexual innuendo. But the low obscenity of silly talk and the “high” obscenity of coarse jesting come from the same kind of heart, the heart given over to moral filthiness.

In light of such clear teaching of God’s Word, it is strange that so many Christians not only discuss but laugh and joke with impunity about almost every form of sexual intimacy, corruption, and perversion. But God’s standard is clear: there must be no filthiness and silly talk, or coarse jesting, which are not fitting.

Instead of being involved in immorality or filthy speaking, the believer’s mouth should be involved in the giving of thanks. Thanksgiving is an expression of unselfishness. The selfish and unloving person does not give thanks because he thinks he deserves whatever good thing he receives. The unselfish and loving person, on the other hand, focuses his life and his concern on the needs of others. Whatever good thing he receives from God or from other people he counts as undeserved and gracious. He is always thankful because his spirit is one of loving and of giving. Instead of using others, he serves them. Instead of trying to turn the innocent into the immoral, he seeks to change the immoral into what is righteous and holy. He is thankful because the holy life is the satisfying life, and people see love for God in the thankful person.

If Christians are known for anything it should be for love expressed toward God and others by unceasing thankfulness (cf. 1 Thess. 5:18, where the injunction is clear: “In everything give thanks; for this is God’s will for you in Christ Jesus”).