I recently read your question and answer entitled, ” Line Upon Line, Precept Upon Precept“. I appreciate the clarification of what is actually being said in context. In Paul’s contrasting of tongues and prophecy (1 Corinthians 14: 21-22), he quotes from Isaiah 28:11 to make the point of tongues being a sign to unbelievers. Can you tell me how you think these two passages connect?
Paul used an interesting reference to prove his point in 1 Cor. 14:21-22 that tongues are a sign for unbelievers, but prophecy is a sign for believers. It seems backward to our understanding until you realize what Isaiah 28:11 means.
In summary, Isaiah 28 has the Lord complaining that His people had made His word into a bunch of rules. Like children who repeat a rhyme without knowing its meaning, they could no longer understand what He was really trying to tell them, which was that their disobedience would lead to judgment. So in verse 11 He said, in effect, “You don’t understand what I’m telling you when I speak in your own language. Therefore I’ll send your enemies against you and they’ll explain it to you in their language, but even then you will not understand.”
In 1 Cor. 14:22-25 Paul explained what this means. When everyone in the Church is speaking in tongues, unbelievers who come in won’t be able to understand what’s going on and will think everyone is crazy. Therefore tongues is a sign for unbelievers to remain unbelievers. This is why Paul cautioned us to be very careful when using tongues in worship (1 Cor. 14:26-28).
But if several people tell an unbeliever something about himself they would have no way of knowing, the unbeliever will realize it came from God, conclude that God is with them, and begin worshiping Him. Therefore prophecy is a sign for an unbeliever to become a believer.