Paul urges them to pursue love and desire spiritual gifts, above all prophecy. The one who speaks in a tongue speaks to God and no one understands him, but the one who prophesies speaks to people for their upbuilding, encouragement and consolation. The one who speaks in a tongue builds up himself; the one who prophesies builds up the church. Paul would like all to speak in tongues, but even more that they prophesy, unless there is interpretation.
He uses the example of the flute, the harp and the trumpet, which are useless without a clear sound. So the Corinthians, eager for gifts, should excel in those that build up the church, and whoever speaks in a tongue should pray to interpret. Paul will pray with the spirit and also with the mind, and would rather speak five words with his mind to instruct others than ten thousand in a tongue. He calls them to be mature in thinking. If all speak in tongues and an outsider comes in, he will say they are out of their minds; but if all prophesy and an unbeliever comes in, he will be convicted, fall on his face and declare that God is among them.
He then gives rules: each brings a psalm, a lesson, a revelation, a tongue or an interpretation, all for building up. If tongues are spoken, let there be two or three, in turn, with an interpreter; if there is none, let them keep silent. Let two or three prophets speak and the others weigh what is said. God is not a God of confusion but of peace.
Verses 34 and 35 ask that women keep silent in the congregation, a much-debated passage read alongside what Paul said about women who pray and prophesy. Paul concludes by encouraging them to desire to prophesy, not to forbid tongues and to do all things decently and in order.