The following is an excerpt from The MacArthur New Testament Commentary on 1 Corinthians 14.

If therefore the whole church should assemble together and all speak in tongues, and ungifted men or unbelievers enter, will they not say that you are mad? But if all prophesy, and an unbeliever or an ungifted man enters, he is convicted by all, he is called to account by all; the secrets of his heart are disclosed; and so he will fall on his face and worship God, declaring that God is certainly among you. (1 Corinthians 14:23–25)

The limited function of the genuine gift of tongues can be seen in the fact that, even during its proper time in history, it could be misused and become a hindrance to worship and to evangelism. If everyone with the gift spoke at once, and ungifted men or unbelievers enter, will they not say that you are made? As in v. 16, I believe that idiotes (ungifted) is better rendered in its more common meaning of unlearned or ignorant.

An unbelieving Gentile would have been turned off if … the whole church should assemble together and all speak in tongues, because he would have seen no meaning in the sign. An unbelieving Jew would have been turned off because of the bedlam and confusion. Mainomai (mad) means to be in a frenzied rage, to be beside oneself in anger. An unbeliever, Gentile or Jew, would go away from such a service thinking it was just another wild and meaningless ritual, much like those of paganism.

Though they were not given for edification, tongues were nevertheless to be understood, not to cause bewilderment. The amazement of the Jewish visitors in Jerusalem at Pentecost was in the fact that they understood what was spoken in tongues in their “own tongues” (Acts 2:11).

On the other hand, if all prophesy, and an unbeliever or an ungifted man enters, he is convicted by all, he is called to account by all. These judicial verbs indicate that preaching the Word brings men to the conviction that the argument is true, and that they will be judged on the basis of their response. Paul continues to contrast tongues with prophecy, again showing prophecy’s superiority. Prophecy is used here in its most general sense of speaking forth God’s Word. When the Word is proclaimed it speaks to men’s hearts and brings conviction of sin, the first step in coming to faith. The convicted person comes to see himself as he really is, because the secrets of his heart are disclosed. His sinful intentions and acts are revealed to him. Consequently, he will fall on his face and worship God, declaring that God is certainly among you. The church’s most powerful testimony is not in its ecstasies, but in its clear proclamation of the powerful Word of God (Heb. 4:12).

When tongues were misused, there was only confusion, frustration, and bewilderment. Unbelievers were repelled and believers were unedified. But prophecy edifies believers and evangelizes unbelievers. God is honored and men are blessed when His Word is clearly declared. Our desire should be that every service, every activity, everything that we say or do in the Lord’s name will cause people to say God is certainly among you.