For he who speaks in a tongue does not speak to men but to God, for no one understands him; however, in the spirit he speaks mysteries.
Therefore let him who speaks in a tongue pray that he may interpret. 14 For if I pray in a tongue, my spirit prays, but my understanding is unfruitful.
Therefore if the whole church comes together in one place, and all speak with tongues, and there come in those who are uninformed or unbelievers, will they not say that you are out of your mind?
Let us expand the verses to see context. Notice how the Corinthians were abusing tongues and misusing what God intended regarding tongues.
I highly suggest that we NOT emulate the church at Corinth in regard to speaking in tongues. Instead, let the evidence within the book of Acts be your barometer in understanding the gift of tongues as God grants it. What Corinth was doing was an abomination.
What I find fascinating is the human condition that is constantly looking for an experiential stimulus to confirm God's presence rather than accept God's word by faith. Why do Christians gravitate toward experiences rather than just faithfully believing regardless of experience?
1 Corinthians 14:6-22
[6]Dear brothers and sisters, if I should come to you speaking in an unknown language, how would that help you? But if I bring you a revelation or some special knowledge or prophecy or teaching, that will be helpful.
[7]Even lifeless instruments like the flute or the harp must play the notes clearly, or no one will recognize the melody.
[8]And if the bugler doesn’t sound a clear call, how will the soldiers know they are being called to battle?
[9]It’s the same for you. If you speak to people in words they don’t understand, how will they know what you are saying? You might as well be talking into empty space.
[10]There are many different languages in the world, and every language has meaning.
[11]But if I don’t understand a language, I will be a foreigner to someone who speaks it, and the one who speaks it will be a foreigner to me.
[12]And the same is true for you. Since you are so eager to have the special abilities the Spirit gives, seek those that will strengthen the whole church.
[13]So anyone who speaks in tongues should pray also for the ability to interpret what has been said.
[14]For if I pray in tongues, my spirit is praying, but I don’t understand what I am saying.
[15]Well then, what shall I do? I will pray in the spirit, and I will also pray in words I understand. I will sing in the spirit, and I will also sing in words I understand.
[16]For if you praise God only in the spirit, how can those who don’t understand you praise God along with you? How can they join you in giving thanks when they don’t understand what you are saying?
[17]You will be giving thanks very well, but it won’t strengthen the people who hear you.
[18]I thank God that I speak in tongues more than any of you.
[19]But in a church meeting I would rather speak five understandable words to help others than ten thousand words in an unknown language.
[20]Dear brothers and sisters, don’t be childish in your understanding of these things. Be innocent as babies when it comes to evil, but be mature in understanding matters of this kind.
[21]It is written in the Scriptures: “I will speak to my own people *** through strange languages *** and through the lips of foreigners. But even then, they will not listen to me,” *** says the lord.
[22]So you see that speaking in tongues is a sign, not for believers, but for unbelievers. Prophecy, however, is for the benefit of believers, not unbelievers.