1 Corinthians 14:18-25

18I thank God that I speak in [unknown] tongues more than all of you;

19nevertheless, in public worship I would rather say five understandable words in order to instruct others, than ten thousand words in a tongue [which others cannot understand].

20Brothers and sisters, do not be children [immature, childlike] in your thinking; be infants in [matters of] evil [completely innocent and inexperienced], but in your minds be mature [adults].

21It is written in the Law, “By men of strange tongues and by the lips of foreigners I will speak to this people, and not even then will they listen to Me,” says the Lord.

22Therefore, [unknown] tongues are [meant] for a [supernatural] sign, not to believers but to unbelievers [who might be receptive]; while prophecy [foretelling the future, speaking a new message from God to the people] is not for unbelievers but for believers.

23So then, if the whole church gathers together and all of you speak in [unknown] tongues, and outsiders or those who are not gifted [in spiritual matters] or unbelievers come in, will they not say that you are out of your mind?

24But if all prophesy [foretelling the future, speaking a new message from God to the people], and an unbeliever or outsider comes in, he is convicted [of his sins] by all, and he is called to account by all [because he can understand what is being said];

25the secrets of his heart are laid bare. And so, falling on his face, he will worship God, declaring that God is really among you.