18 I thank my God I speak with tongues more than you all;
19 yet in the church I would rather speak five words with my understanding, that I may teach others also, than ten thousand words in a tongue.
20 Brethren, do not be children in understanding; however, in malice be babes, but in understanding be mature.
21 In the law it is written: “With men of other tongues and other lips I will speak to this people; and yet, for all that, they will not hear Me,” says the Lord.
22 Therefore tongues are for a sign, not to those who believe but to unbelievers; but prophesying is not for unbelievers but for those who believe.
I speak with tongues (v.18) — There is no other mention of this in Scripture.
do not be (v.20) = cease to be — In exalting the importance of those who speak in tongues, the Corinthians were behaving as children, which let to anger.
children (v.20) — 1 Corinthians 13:11
malice (v.20) — a stronger word than mere malice — When it came to anger, pride and jealousy, they were to behave as if in babyhood
mature (v.20) — The same word is translated “perfect” in 1 Corinthians 2:6.
in the law (v.21) — Isaiah 28:11-12
There is nothing approaching consensus on this passage in my commentaries, and Stam even skips over verses 21 and 22 entirely, to my surprise because I think this is central to understanding the whole passage.
First, Paul says he speaks in tongues more than any of them. There is no other mention of this in Scripture, and he obviously wasn’t in the practice of doing it in the church or he wouldn’t have needed to tell them. In addition, he goes on in the next verse to say how much more valuable it is to speak clearly. So what does it mean? Since I think the gift of tongues is always an actual language, my guess is that Paul, as he traveled around, came in contact with people who didn’t speak the languages he knew — certainly Hebrew and Greek, probably Latin, maybe others — so through the Holy Spirit, he spoke to them in their own tongue.
What about verses 21 and 22? The quote in verse 21 is from Isaiah 28:11-12: For with stammering lips and another tongue He will speak to this people, to whom He said, “This is the rest with which you may cause the weary to rest,” and, “This is the refreshing”; yet they would not hear.
The passage in Isaiah is about judgment coming to Israel because of their unbelief. Some commentaries say that the other tongues are those of invading nations who would conquer Israel, which certainly happened.
Paul says that, in Corinth, they are a sign to those who do not believe. Some commentaries mention this but don’t go into detail. The one commentary that does, DeHaan’s, says that the unbelief spoken of here is speaking of Christians who have doubts verses Christians who don’t, but that doesn’t make a lot of sense to me.
So what does it mean? My best guess, which I’m willing to change if I see a good reason to, leads back to my contention that many of the issues in the Corinthians church came from it’s mixed congregation — Gentiles saved by grace and kingdom Jews. The fact that Gentiles were being given a gift by the Holy Spirit to speak in other languages was a sign to any unbelieving Jews in the congregation — and in the town — that judgment was coming on the nation. This judgment, which Paul proclaims in Acts 28, consisted of the nation of Israel being set aside for the remainder of the age of grace. And since Acts 28 occurred not long after Paul wrote this, tongues, as a sign, were fading quickly.