{10} Wherefore tongues are for a sign, not to them that believe, but to them that believe not: but prophesying serveth not for them that believe not, but for them which believe.

(10) The conclusion: therefore the gift of tongues serves to punish the unfaithful and unbelievers, unless it is referred to prophecy (that is to say, to the interpretation of scripture) and that what is spoken is by the means of prophecy is understood by the hearers.

People's New Testament

14:22 Wherefore tongues are for a sign... to them that believe not. They are a sign to unbelievers, who are moved when they hear the gospel spoken in their tongue by men who have never learned it and do not understand it.

Wesley's Notes

14:22 Tongues are intended for a sign to unbelievers - To engage their attention, and convince them the message is of God. Whereas prophecy is not so much for unbelievers, as for the confirmation of them that already believe.

Jamieson-Fausset-Brown Bible Commentary

22. Thus from Isaiah it appears, reasons Paul, that "tongues" (unknown and uninterpreted) are not a sign mainly intended for believers (though at the conversion of Cornelius and the Gentiles with him, tongues were vouchsafed to him and them to confirm their faith), but mainly to be a condemnation to those, the majority, who, like Israel in Isaiah's day, reject the sign and the accompanying message. Compare "yet . will they not hear Me" (1Co 14:21). "Sign" is often used for a condemnatory sign (Eze 4:3, 4; Mt 12:39-42). Since they will not understand, they shall not understand.

prophesying . not for them that believe not, but . believe-that is, prophesying has no effect on them that are radically and obstinately like Israel (Isa 28:11, 12), unbelievers, but on them that are either in receptivity or in fact believers; it makes believers of those not wilfully unbelievers (1Co 14:24, 25; Ro 10:17), and spiritually nourishes those that already believe.

Matthew Henry's Concise Commentary

14:15-25 There can be no assent to prayers that are not understood. A truly Christian minister will seek much more to do spiritual good to men's souls, than to get the greatest applause to himself. This is proving himself the servant of Christ. Children are apt to be struck with novelty; but do not act like them. Christians should be like children, void of guile and malice; yet they should not be unskilful as to the word of righteousness, but only as to the arts of mischief. It is a proof that a people are forsaken of God, when he gives them up to the rule of those who teach them to worship in another language. They can never be benefitted by such teaching. Yet thus the preachers did who delivered their instructions in an unknown tongue. Would it not make Christianity ridiculous to a heathen, to hear the ministers pray or preach in a language which neither he nor the assembly understood? But if those who minister, plainly interpret Scripture, or preach the great truths and rules of the gospel, a heathen or unlearned person might become a convert to Christianity. His conscience might be touched, the secrets of his heart might be revealed to him, and so he might be brought to confess his guilt, and to own that God was present in the assembly. Scripture truth, plainly and duly taught, has a wonderful power to awaken the conscience and touch the heart.