1 CORINTHIANS CHAPTER 14.
The Use of Spiritual Gifts in Public Worship. 1 Cor. 14, 1-40.
Strange tongues may become dangerous: V. 21. In the Law it is written, With men of other tongues and other lips will I speak unto this people; and yet for all that will they not hear Me, saith the Lord. V. 22. 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.
To give the Corinthians the right understanding of the gift of tongues, Paul now introduces a Scripture-passage: In the Law, in the book of the Old Testament Scriptures, it is written, In men that speak a strange language and in lips of aliens I will speak to this people, and even so they will not listen to Me, give Me an attentive ear, says the Lord, Is. 28, 11. 12.
In the original passage "the drunken Israelites are mocking in their cups the teaching of God through His prophet, as though it were fit only for an infant school; in anger, therefore, He threatens to give His lessons through the lips of foreign conquerors."
Paul quotes the passage to show that the speaking of tongues may work harm in the Church: Therefore the strange tongues are a sign, they serve for a sign, not to the believing, but to the unbelievers; by this gift God manifested His presence, not so much for the sake of the members of the congregation as for those that were still unbelievers. When God speaks in such an unintelligible way, He exhibits Himself "not as one that is opening His thoughts to the faithful, but as one who is shutting Himself up from those who will not believe."
So the hardened unbelievers, having rejected the clear and unmistakable preaching of the Cross, find themselves confirmed, and even justified, according to their opinion, by this phenomenon.
On the other hand, the gift of prophecy is not for the unbelievers, but for the believing. It is not only that the proper exposition of the Gospel of salvation works faith and strengthens faith, but also that it serves as a sign of the mercy of God and changes unbelievers into believers. So Paul discountenances the gift of tongues and disapproves of its use in public services, because the purpose of edification is not accomplished through its exercise.