1 Corinthians 14:22-24

22So the gift to speak in different languages is like a sign. It shows God's power to people who do not believe in him. It is not a sign to help believers. But the gift to speak clear messages from God shows his power to believers. It is not a sign for those people who do not believe.

23Think about what happens when the whole church meets together. Perhaps some people come in who do not believe in God. Or perhaps they have not learned much about God. If all of you are speaking in strange languages, those visitors would not understand. They would say that you are all crazy!

24But if all of you are speaking clear messages from God, a visitor will understand you. He may not believe in God. He may not have learned much about God. But he will hear God's message. He will understand that he has done wrong things. He will know that God will judge him. He will learn this from what all of you are saying.