2For the person who speaks in another language is not speaking to men but to God, since no one understands him; however, he speaks mysteries in the Spirit.
5I wish all of you spoke in other languages, but even more that you prophesied. The person who prophesies is greater than the person who speaks in languages, unless he interprets so that the church may be built up.
6But now, brothers, if I come to you speaking in other languages, how will I benefit you unless I speak to you with a revelation or knowledge or prophecy or teaching?
7Even inanimate things that produce sounds--whether flute or harp--if they don't make a distinction in the notes, how will what is played on the flute or harp be recognized?
15What then? I will pray with the spirit, and I will also pray with my understanding. I will sing with the spirit, and I will also sing with my understanding.
16Otherwise, if you praise with the spirit, how will the uninformed person say "Amen" at your giving of thanks, since he does not know what you are saying?
21It is written in the law: I will speak to these people by people of other languages and by the lips of foreigners, and even then, they will not listen to Me, says the Lord.
22It follows that speaking in other languages is intended as a sign, not for believers but for unbelievers. But prophecy is not for unbelievers but for believers.
23Therefore, if the whole church assembles together and all are speaking in other languages and people who are uninformed or unbelievers come in, will they not say that you are out of your minds?
26What then is the conclusion, brothers? Whenever you come together, each one has a psalm, a teaching, a revelation, another language, or an interpretation. All things must be done for edification.