1 Corinthians 14:22-24

22Tongues, then, are a sign, not for believers, but for unbelievers. Prophecy, however, is for believers, not for unbelievers.

23So if the whole church comes together and everyone speaks in tongues, and some who are uninstructed or some unbelievers come in, will they not say that you are out of your minds? 24But if an unbeliever or uninstructed person comes in while everyone is prophesying, he will be convicted and called to account by all,