One of the purposes of 1 Cor 14 is to describe a responsible use of unknown tongues.
An "unknown tongue" or “speaking in tongues” is speaking via the Spirit in a language unknown to the hearers. This is not merely a foreign language; it is a language unknown to humans. Someone during a church meeting is impressed by to Spirit to "speak in tongues" and most, if not all, do not know what is being said. "Speaking in tongues" is often a point of confusion and contention among Christians.
Verse 14:6 prefers the use of these types of speech to unknown tongues: Revelation, the definition or explanation of a truth from God; Knowledge, the expansion in understanding of the revelation; and Prophecy.
1 Cor 14:3 defines Prophecy as: Edification, the result of revelation and knowledge, Exhortation, the urging to use the revelation and knowledge; and Consolation, the direction and comfort we should obtain from using revelation and knowledge.
Notice this is different from how many usually define Prophecy: a speech that predicts the future.
1 Corinthians 14 (NASB)
3. But one who prophesies speaks to men for edification and exhortation and consolation. 4. One who speaks in a tongue edifies himself; but one who prophesies edifies the church . . . 6. But now, brethren, if I come to you speaking in tongues, what will I profit you unless I speak to you either by way of revelation or of knowledge or of prophecy or of teaching . . . 9. So also you, unless you utter by the tongue speech that is clear, how will it be known what is spoken? For you will be speaking into the air.
