15 So what shall I do? I will pray with my spirit, but I will also pray with my understanding; I will sing with my spirit, but I will also sing with my understanding. 16 Otherwise when you are praising God in the Spirit, how can someone else, who is now put in the position of an inquirer, say "Amen" to your thanksgiving, since they do not know what you are saying? 17 You are giving thanks well enough, but no one else is edified. 18 I thank God that I speak in tongues more than all of you. 19 But in the church I would rather speak five intelligible words to instruct others than ten thousand words in a tongue. 20 Brothers and sisters, stop thinking like children. In regard to evil be infants, but in your thinking be adults.
21 In the Law it is written: "With other tongues and through the lips of foreigners I will speak to this people, but even then they will not listen to me, says the Lord." 22 Tongues, then, are a sign, not for believers but for unbelievers; prophecy, however, is not for unbelievers but for believers. 23 So if the whole church comes together and everyone speaks in tongues, and inquirers or unbelievers come in, will they not say that you are out of your mind? 24 But if an unbeliever or an inquirer comes in while everyone is prophesying, they are convicted of sin and are brought under judgment by all, 25 as the secrets of their hearts are laid bare. So they will fall down and worship God, exclaiming, "God is really among you!"
14:16 The Greek word for "inquirer" is a technical term for someone not fully initiated into a religion; also in verses 23 and 24.
14:21 Isaiah 28:11,12