16. Otherwise, if you bless and render thanks with [your] spirit [thoroughly aroused by the Holy Spirit], how can anyone in the position of an outsider or he who is not gifted with [interpreting of unknown] tongues, say the Amen to your thanksgiving, since he does not know what you are saying? [I Chron. 16:36; Ps. 106:48.]
17. To be sure, you may give thanks well (nobly), but the bystander is not edified [it does him no good].
18. I thank God that I speak in [strange] tongues (languages) more than any of you or all of you put together;
19. Nevertheless, in public worship, I would rather say five words with my understanding and intelligently in order to instruct others, than ten thousand words in a [strange] tongue (language).
20. Brethren, do not be children [immature] in your thinking; continue to be babes in [matters of] evil, but in your minds be mature [men].
21. It is written in the Law, By men of strange languages and by the lips of foreigners will I speak to this people, and not even then will they listen to Me, says the Lord. [Isa. 28:11, 12.]
22. Thus [unknown] tongues are meant for a [supernatural] sign, not for believers but for unbelievers [on the point of believing], while prophecy (inspired preaching and teaching, interpreting the divine will and purpose) is not for unbelievers [on the point of believing] but for believers.
23. Therefore, if the whole church assembles and all of you speak in [unknown] tongues, and the ungifted and uninitiated or unbelievers come in, will they not say that you are demented?
24. But if all prophesy [giving inspired testimony and interpreting the divine will and purpose] and an unbeliever or untaught outsider comes in, he is told of his sin and reproved and convicted and convinced by all, and his defects and needs are examined (estimated, determined) and he is called to account by all,
25. The secrets of his heart are laid bare; and so, falling on [his] face, he will worship God, declaring that God is among you in very truth.
26. What then, brethren, is [the right course]? When you meet together, each one has a hymn, a teaching, a disclosure of special knowledge or information, an utterance in a [strange] tongue, or an interpretation of it. [But] let everything be constructive and edifying and for the good of all.