John Calvin Commentary 1 Corinthians 14:22

"Wherefore tongues are for a sign, not to them that believe, but to the unbelieving: but prophesying [is for a sign], not to the unbelieving, but to them that believe." — 1 Corinthians 14:22 (ASV)

Therefore tongues are for a sign. This passage may be explained in two ways: by considering the word therefore as referring merely to the preceding sentence, or as having a general bearing on the whole of the previous discussion. If it is a particular inference, the meaning will be: “You see, brothers, that what you so eagerly desire is not a blessing bestowed by God upon believers, but a punishment by which he inflicts vengeance upon unbelievers.” In this way, Paul would not be viewed as encompassing the use of tongues under all circumstances, but simply as touching upon what had in one instance occurred. If anyone, however, prefers to extend it to the whole discussion, I have no objection, though I do not dislike the former interpretation.

Taking it in a general way, the meaning will be: “Tongues, insofar as they are given for a sign—that is, for a miracle—are appointed not properly for believers, but for unbelievers.” The advantages derived from tongues were various. They served a practical purpose: ensuring that the diversity of tongues would not prevent the Apostles from disseminating the gospel throughout the whole world. Consequently, there was no nation with which they could not have fellowship.

They also served to move or terrify unbelievers by the sight of a miracle. For the design of this miracle, equally with others, was to prepare those who were still at a distance from Christ for rendering obedience to him. Believers, who had already devoted themselves to his doctrine, did not have as much need of such preparation.

Therefore, the Corinthians misused that gift, elevating it improperly and out of its correct place. In doing so, they allowed prophecy to be neglected in the meantime. Prophecy, however, was uniquely and specially set apart for believers and, therefore, ought to be familiar to them. For with tongues, they looked no further than the miracle.