How can you say that the gift of tongues is meant for “an audience of unbelievers”, when in the very next verse (1 Corinthians 14:23) it says that if an unbeliever walks in on everyone speaking in tongues they will think you are mad?
Actually, I will beg to differ that Verse 23 supports Verse 22.
Let's back up a bit to verse 21
In the Law it is written, “By people of strange tongues and by the lips of foreigners will I speak to this people, and even then they will not listen to me, says the Lord.”
"This people" refers to the Jews or God's people (believers). Paul is using Verse 21 (or the reference from Isaiah 28:11-12) to logically point that because his people do not listen, then
the use of tongues is meant for unbelievers.
Again there is no ambiguity in verse 22:
Thus tongues are a sign not for believers but for unbelievers, while prophecy is a sign not for unbelievers but for believers.
Verse 23 gives us an example and shows us why:
If, therefore, the whole church comes together and all speak in tongues, and outsiders or unbelievers enter, will they not say that you are out of your minds?
Let's say I'm a member of this congregation in Verse 23. And there is a stirring by the Holy Spirit to speak in tongues. The Holy Spirit is one Spirit and moves in oneness with God and Christ. I start speaking in tongues, everyone in my pew starts speaking in tongues, and the preacher at the pulpit starts speaking in tongues, we would be speaking in one accord but in different languages and utterances? To the unbeliever or the outsider, if he chances upon this scene happening within the church, wouldn't he conclude that we are a raving, mad bunch? Furthermore, there is no edification among believers to speak in tongues because we do not understand ourselves or each other (without another gift of interpretation of tongues). Therefore the conclusion is that the use of tongues, cannot be for believers within the congregation.
This example shows that speaking tongues among believers does not make sense. Hence, tongues is meant for unbelievers.
Verse 24-25, on the other hand shows us an opposite setting.
But if all prophesy, and an unbeliever or outsider enters, he is convicted by all, he is called to account by all, the secrets of his heart are disclosed, and so, falling on his face, he will worship God and declare that God is really among you.
Let's say I'm a member of this congregation in Verse 24-25. And there is a stirring by the Holy Spirit to prophesy. The Holy Spirit is one Spirit and moves in oneness with God and Christ. I start speaking prophesying, everyone in my pew starts prophesying, and the preacher at the pulpit starts prophesying, we would be prophesying in one accord and in the same language. To the unbeliever or the outsider, if he chances upon this scene happening within the church and he understands the language that is being used for prophesy, he will leave at the very least concluding that God is among us and in the best-case scenario, a repentant and new believer in Christ.
This example shows that prophesying among believers makes sense. Hence, prophesy is meant for believers.
I hope my not-so-short reply will convince some in this post that I have at least given this passage serious thought before coming to this conclusion.