15 What should I do then? I will pray with the spirit, but I will pray with the mind also; I will sing praise with the spirit, but I will sing praise with the mind also. 16 Otherwise, if you say a blessing with the spirit, how can anyone in the position of an outsider say the "Amen" to your thanksgiving, since the outsider does not know what you are saying? 17 For you may give thanks well enough, but the other person is not built up. 18 I thank God that I speak in tongues more than all of you; 19 nevertheless, in church I would rather speak five words with my mind, in order to instruct others also, than ten thousand words in a tongue. 20 Brothers and sisters, do not be children in your thinking; rather, be infants in evil, but in thinking be adults.
21 In the law it is written, "By people of strange tongues and by the lips of foreigners I will speak to this people; yet even then they will not listen to me," says the Lord. 22 Tongues, then, are a sign not for believers but for unbelievers, while prophecy is not for unbelievers but for believers. 23 If, therefore, the whole church comes together and all speak in tongues, and outsiders or unbelievers enter, will they not say that you are out of your mind? 24 But if all prophesy, an unbeliever or outsider who enters is reproved by all and called to account by all. 25 After the secrets of the unbeliever's heart are disclosed, that person will bow down before God and worship him, declaring, "God is really among you."
Matthew Henry's Commentary on 1 Corinthians 14:15-25
Commentary on 1 Corinthians 14:15-25
(Read 1 Corinthians 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.