1 Corinthians 14:22-25
22 Tongues, then, are a sign, not for believers but for unbelievers; prophecy, however, is for believers, not for unbelievers.
23 So if the whole church comes together and everyone speaks in tongues, and some who do not understand or some unbelievers come in, will they not say that you are out of your mind?
24 But if an unbeliever or someone who does not understand comes in while everybody is prophesying, he will be convinced by all that he is a sinner and will be judged by all,
25 and the secrets of his heart will be laid bare. So he will fall down and worship God, exclaiming, “God is really among you!”