For with stammering lips and a strange tongue will he speak to this people;
Isaiah has just described priests and prophets too drunk to take in God's plain teaching. They would not listen to words they understood, so God says He will speak to them in a language they cannot follow — but whose language is it, and why?
The verses just before speak of teaching in small, repeated portions, like feeding a newly weaned child. They ignored that patient method. The strange tongue is what comes next.
God had met their weakness and fed them with infants' food, but it was all in vain… Another way of dealing with them is needed, and it will surely come… He would punish them, not with the childlike teaching they had despised, but with the foreign speech of enemies. They would not have His words of rest for the weary, so they had to have a nation whose language they did not understand. It was a judgment on their unbelief.
Where the ESV reads "people of strange lips," older translations read "stammering lips." No other place in the Old Testament looks ahead to people speaking a language they never learned.
Speaking in other languages without having learned them does not occur in the Old Testament. Only one prophecy about it is found (Isaiah 28:11-13), and if 1 Corinthians 14:21 did not quote it with direct reference to speaking in tongues, we would probably never have connected the two. The priests and prophets in Israel were no longer open to true knowledge and God's message (v. 7-10). So God would speak to them through people whose speech they could not understand, in a strange tongue. These are their enemies, who would bring judgment on them.
Commentators differ. One reads the strange speech as God stooping to the crowd, not as the noise of an invading army:
The prophet goes on to show that God might stoop to deal with the mass of the people in this simple way, even using "stammering lips and another tongue." Yet they refuse to hear, and they are broken.
Nothing else in the Old Testament speaks of people using languages they never learned. Paul quotes these words in 1 Corinthians 14, and without that quotation the link would be easy to miss.
The Apostle quotes Isaiah 28:11-12 freely. He shows that in the day of Israel's failure, when the prophets had gone wrong, God spoke to them in the languages of foreigners. This was a sign of the unbelief of those who would not hear the plain word of God. So when the gift of tongues was used at the start of Christianity, it was a sign to unbelievers, not to believers, and it left the hearer without excuse.
The believers in Corinth preferred tongues to prophecy. Set beside what the verse first meant for Israel, that choice looks strange.
There God warns the Jews, who were slow to listen to His prophets, that He would speak to them with the stammering lips of foreigners. Such a tongue spoken to Israel was a sign of their humiliation, and of God's judgment. How wrong-headed, then, for the believers in Corinth to turn away from God speaking in prophecy to build them up, and to turn instead to tongues they could not understand! They took their pleasure as Christians in what was God's solemn threat to His ancient people.
Centuries later the same sign came back. This time the good news went out in the languages of other nations.
God would use foreign tongues to humble them, not to lift them up. He meant to wake them out of their unbelief, yet they would not hear. Now God had given Israel a fresh sign in speaking with tongues: the gospel of grace went out in the languages of other nations. This showed that the gospel was not only for Israel, but for the whole world.
Verse 13 tells what the strange tongue leads to — falling backward, breaking, being snared. The pattern is wider than Isaiah's own generation.
Resistance brings blindness on those who resist, and the greater the light they refuse, the greater the blindness. If a person receives the first testimony, more is always added… The more God shows Himself, the more the heart's natural opposition comes out. Those who receive the first grace receive the rest until glory, and go from strength to strength.
- Refusal. God had taught Israel gently, a little at a time, and they would not take it in.
- Reversal. They despised plain words, so God turned to speech they could not follow. Most read this as the voice of invading enemies. Some read it as God still stooping to their level.
- Sign. Paul uses the verse in 1 Corinthians 14. A foreign tongue was a sign for unbelievers, and it left the hearer without excuse.
- Reach. The sign came back when the gospel went out in the languages of other nations. The message was not for Israel alone.
- Result. Light refused hardens; light received grows. That is the warning and the promise carried by one strange-sounding verse.
to whom he said, This is the rest cause the weary to rest; and this is the refreshing. But they would not hear.
God had spoken to His people in the plainest way possible, offering them rest and relief, and they turned it down. Their refusal is why He said He would speak next through foreign lips — words Paul later quoted to correct a church that prized tongues.
The chapter opens with priests and prophets who had lost their grip on truth. God came down to their level and taught them like small children. One writer shows what followed when they refused even that.
God had met their weakness in vain and fed them with infants' food... He would whip them not with the childlike instruction they had slighted, but with the foreign tones of enemies. They would not have His words of rest for the weary; they had to have a nation whose speech they did not understand. It was a judgment on their unbelief.
"They would not hear" is the hinge of the chapter. One writer sets out the principle behind that refusal.
Resistance brings blindness on those who resist. That blindness is all the greater because it matches the light they refused. If the first testimony is received, more is always added, for it is given to him who has, and he shall have more abundance... The more God shows Himself, the more the heart's natural opposition shows itself... No blindness is like the blindness that comes from resisting the light and holding on to your own will while it shines... Those who receive the first grace receive the rest until glory, and go from strength to strength.
If they will not hear God in words they understand, He will speak in words they cannot. The chapter's own context shows who those speakers were.
The sense of the passage becomes clear from its context. The priests and prophets in Israel were no longer open to true knowledge and the divine report (vv. 7-10). So God would speak to them through people whose speech they could not understand, in a strange tongue. These are their enemies, who would bring judgment on them. The Holy Spirit uses this passage in 1 Corinthians 14 to make clear that tongues are a sign to unbelievers and not to believers (vv. 21, 22).
The pattern did not stay in Isaiah's day. One writer sees the Lord's own ministry fulfilling these verses.
In John 9:39 the Lord fulfils Isaiah 28:9-13. The judgment is a sifting process. Compare Luke 2:34: "for the fall and rising of many in Israel," leaving men either better or worse.
Paul quotes these words in a letter about speaking in tongues. The Corinthians prized what God had sent as a threat.
Such a tongue speaking to Israel was a sign of their humiliation and of God's judgment. What perversity, then, in the saints at Corinth! They turned away from God speaking in prophecy to build them up, and turned to tongues they could not understand. They took pleasure as Christians in what God had meant as a solemn threat to His ancient people, because they stubbornly refused to listen!
Another writer follows the same refusal into the day when tongues returned as a sign.
God would use foreign tongues to humble them, not to exalt them. By this means He sought to wake them out of their unbelief. Yet they would not hear. Now God had given Israel a fresh sign in speaking with tongues. Preachers proclaimed the gospel of grace in Gentile languages. This showed that the gospel was not only for Israel but for all the world... And unbelieving Israel still would not hear.
- Offered. God met a stumbling people at their level. He fed them "infants' food" and held out rest for the weary.
- Refused. They would not hear. God held out rest, and they turned it down.
- Replaced. Instead of rest they got speech they could not understand. The tongues of enemies came to humble them, not to exalt them.
- Repeated. The refusal did not end with Isaiah. Writers trace the same sifting judgment into the Gospels, and the same deafness when tongues sounded again with the gospel.
- Reversed for faith. Refused light hardens. Received light multiplies: those who take the first grace keep receiving until glory.