The following is an excerpt from The MacArthur New Testament Commentary on Matthew 12.

And I say to you, that every careless word that men shall speak, they shall render account for it in the day of judgment. For by your words you shall be justified, and by your words you shall be condemned. (12:36–37)

Because men’s words are an accurate gauge of their hearts, they shall render account for their words in the day of judgment. It is by his words that a person is either justified or condemned. Salvation and condemnation are not produced by words or deeds, but they are manifested by them. Words and deeds are objective, observable evidence of a person’s spiritual condition. In the day of judgment, that future general time when the Lord evaluates who belongs in and out of His eternal kingdom, the criteria will include the speech of every person.

The consistent teaching of both Old and New Testaments is that the only way of salvation is by God’s grace working through man’s faith. Jesus’ point is not that words are the basis of salvation or condemnation but that they are reliable evidence of the reality of salvation, The speech of a redeemed person will be different, because it comes from his renewed heart. Pure, wholesome, praising speech shows a new heart.

We are not saved by good works, but we are saved for “good works, which God prepared beforehand, that we should walk in them” (Eph. 2:10). In the same way, we are saved for good words. “With the heart man believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation” (Rom. 10:10), which, in turn, results in “obedience … by word and deed” (15:18). Salvation will produce good words, and it is for that reason and in that sense that words bring justification or condemnation.

The ungodly will be eternally condemned for their speech. Apart from what they did, what they said is enough evidence of their unregenerate heart to send them to hell. Jesus does not limit this warning to extremes such as blasphemy, but makes explicit that men will render account for every careless word that they speak-whether or not it is immoral, vulgar, cruel, or blasphemous. They will have to render account even for words that are careless.

The basic meaning of argos (careless) is useless, barren, unproductive, or otherwise worthless. Such words include those that are flippant, irresponsible, or in any way inappropriate. Hypocritical words are among the most careless and worthless that men speak and are, unfortunately, among the most common. When men self-consciously keep their vocabulary orthodox, moral, and evangelically acceptable while among fellow Christians-for the sake of impressing them or to keep from embarrassing ourselves-those words are careless and worthless in God’s sight, and He will render them against their account. The calculated hypocrisy of such “holy talk” is a stench in His nostrils.

The Christian’s speech will reflect God’s transforming work in the heart; but because of our unredeemed humanness, it still needs constant care if it is to be increasingly spiritual, wholesome, fitting, kind, sensitive, loving, purposeful, edifying, and truthful. With the Psalmist he should pray, “Set a guard, O Lord, over my mouth; keep watch over the door of my lips” (Ps. 141:3).

But for the unbeliever, all the words of his unredeemed heart are worthless as far as spiritual value is concerned. His evil words are obviously worthless. Among the most common evil words are those that express lust (Prov. 5:3–4); deceit (Jer. 9:8); cursing and oppression (Ps. 10:7); lying (Prov. 6:12; 12:22); destruction (Prov. 11:11); vanity (2 Pet. 2:18); flattery (Prov. 26:28); foolishness (Prov. 15:2); verbosity (Eccles. 10:14); falsehood (Titus 1:11); pride (Job 35:12); vulgarity (Col. 3:8); hatred (Ps. 109:3); and gossip (Prov. 26:20).

For the unbeliever, careless and worthless words also include those that are otherwise good. Although his words of love, encouragement, comfort, and kindness may be sincere and greatly helpful to others, they are of no spiritual value to him because they do not come from a redeemed and righteous heart. No spiritually good thing can come from a heart that is spiritually evil.-as Jesus has just pointed out.

A person can get a good indication of his spiritual condition by listening to his own words. A Christian can fall into evil words just as he can fall into evil deeds, but his customary speaking will be pure just as his customary activities will be righteous.

Although this passage has application to both the saved and the unsaved-to the “good man” and the “evil man”-Jesus’ thrust here is directed to unbelievers, represented in the extreme by the blaspheming Pharisees.

The day of judgment for unbelievers culminates at the great white throne judgment, the ultimate and eternal judgment at which all unbelievers shall be condemned. Christians’ sins will have all been dealt with at Calvary, dismissed by the atoning blood of Christ applied on behalf of their faith. Every Christian has sinned with his tongue after salvation, but Christ’s sacrifice is sufficient to cover that and every other sin he commits. The evil words and deeds of unbelievers, however, will remain to stand in evidence against them. Like the unfaithful slave in Jesus’ parable, unbelievers will be judged by their own words (Luke 19:22).

In his vision of the great white throne judgment John saw “the great and the small, standing before the throne, and books were opened; and another book was opened, which is the book of life; and the dead were judged from the things which were written in the books, according to their deeds. … And if anyone’s name was not found written in the book of life, he was thrown into the lake of fire” (Rev. 20:12, 15). When the record books are scanned, no good deeds will be listed by the names of unbelievers; and when the book of life is scanned, not even their names will appear. The books that report deeds and the book that reports faith will alike testify against them.

Scientists theorize that sound waves are never completely lost but gradually fade beyond detection. With sufficiently sensitive instruments, every word ever spoken in the history of mankind presumably could be retrieved. How much more certain can we be that in God’s infallible records every word and deed of mankind is perfectly preserved for use as evidence in the coming judgment!