Brethren, be not children in understanding - Be not childish; do not behave like little children. They admire, and are astonished at what is striking, novel, and what may be of no real utility. They are pleased with anything that will amuse them, and at little things that afford them play and pastime. So your admiration of a foreign language and of the ability to speak it, is of as little solid value as the common sports and plays of boys. This, says Doddridge, is an admirable stroke of oratory, and adapted to bring down their pride by showing them that those things on which they were disposed to value themselves were “childish.” It is sometimes well to appeal to Christians in this manner, and to show them that what they are engaged in is “unworthy” the dignity of the understanding - unfit to occupy the time and attention of an immortal mind. Much, alas! very much of that which engages the attention of Christians is just as unworthy of the dignity of the mind, and of their immortal nature, as were the aims and desires which the apostle rebuked among the Christians at Corinth. Much that pertains to dress, to accomplishment, to living, to employment, to amusement, to conversation, will appear, when we come to die, to have been like the playthings of “children;” and we shall feel that the immortal mind has been employed, and the time wasted, and the strength exhausted in that which was foolish and puerile.
Howbeit in malice be ye children - This is one of Paul’s most happy turns of expression and of sentiment. He had just told them that in one respect they ought not to be children. Yet, as if this would appear to be speaking lightly of children - and Paul would not speak lightly of anyone, even of a child - he adds, that in “another” respect it would be well to be like them - nay, not only like children, but like “infants.” The phrase “be ye children,” here, does not express the force of the original νηπιάζετε nēpiazete. It means, “be infants,” and is emphatic, and was used, evidently, by the apostle of design. The meaning may be thus expressed. “Your admiration of foreign languages is like the sports and plays of “childhood.” In this respect be not children (παιδίᾳ paidia); be men! Lay aside such childish things. Act worthy of the “understanding” which God has given you. I have mentioned children. Yet I would not speak unkindly or with contempt even of them. “In one respect” you may imitate them. Nay, you should not only be like “children,” that are somewhat advanced in years, but like “infants.” Be as free from malice, from any ill-will toward others, from envy, and every improper passion, as they are.” This passage, therefore, accords with the repeated declaration of the Saviour, that in order to enter into heaven, it was needful that we should become as little children; Matthew 18:3.
Be men - Margin, “Perfect, or of a riper age” (τέλειοι teleioi). The word means full-grown men. Act like them whose understandings are mature and ripe.