“Make the heart of this people fat​.” In this context, the “heart” refers to the mind and thoughts. The student of the Bible must learn to think of the “heart” as the center of rational thought rather than the seat of emotion (see commentary on Prov. 15:21). So the phrase could be easily translated, “Make the minds of these people ‘fat,’” (i.e., unresponsive, dull, stupid, stubborn).

Note that God tells Isaiah to make the heart of the people fat. This is not God’s doing, God tells Isaiah to do it. But how could Isaiah make the people’s heart fat and their ears heavy and shut their eyes? He couldn’t. This is the idiom of permission. In this case, Isaiah is told to do something when in fact he can only stand by and watch it happen, (in scholarly jargon, “permit” it to happen). It is important to keep in mind when reading verses that say things such as God (or in this case, Isaiah) hardened someone’s heart, or covered their ears, or blinded their eyes, it is the people who actually did those things to themselves. God does not harden someone’s heart and then punish him for having a hardened heart, and Isaiah certainly had no ability to do that. Besides, that would be totally against the loving nature of God and his servants. Verses that say something such as we see here in Isaiah 6:10-11, or that God hardened someone’s heart, are written using standard Hebrew language and customs and are using the Semitic “idiom of permission. The “idiom of permission” is a name given by scholars to the particular Semitic manner of speaking in which someone is said to actively do what he only allowed to be done.

Why does the Bible say that God directed Isaiah to make the people’s hearts dull and close their eyes and ears if Isaiah does not have the power to do that? The idea behind the idiom of permission is that when the truth is spoken to someone then they have to make the choice as to how to respond, and that response can be openly seen. This is the same idea as we see in Romans when it says that without the law sin is dead. The law was good, but when the law came then “sin came alive” because now the person’s actions were clearly sin—breaking the law—and those actions would be obvious to everyone. Paul wrote in Romans, “When the commandment came, sin came alive, and I died. And I discovered that the commandment that was given for life actually resulted in death” (Rom. 7:9-10). So Romans shows us that people have sinful hearts, but it is when the law comes into the picture that people clearly go against God’s laws and sin. When the commandment comes and people break it rather than obey it, then they are clearly sinning, and furthermore, their sin and guilt become obvious.

So it is with the idiom of permission. God did not harden Pharaoh’s heart, but when God commanded Pharaoh to let Israel go, Pharaoh hardened his own heart against God, which also revealed the pride and arrogance in Pharaoh’s heart. Similarly, Isaiah’s prophetic word did not make the hearts of the people of Israel obstinate against God, but when Isaiah prophesied and gave them the Word of God they made the choice to ignore and defy it, and as Isaiah prophesied over and over, the people became more and more obstinate and disobedient, just like Pharaoh did. Isaiah’s prophetic word did not make the people’s heart fat and obstinate, but it forced the people to openly defy God and it certainly revealed their arrogant hearts. Thus, God’s command to Isaiah to “make” the people’s hearts fat is actually more like “speak the truth so that the people will have to make a choice between me and them, and any arrogance in their heart will be revealed.” Similarly, Jesus taught in parables so that his listeners would make the choice between God and themselves—would they make the effort to understand the parables or just go on their merry way—and the hearts of the people would be clearly revealed. Humble and godly people heard the parables and responded to them, while the arrogant and prideful people did not make the effort to understand them, which revealed the posture of their hearts (cp. Mark 4:11-12).

So God did not reach into Pharaoh’s heart and harden it (cp. Exod. 4:21), but He allowed Pharaoh to harden his own heart (actually, Pharaoh had free will and God could not stop him from hardening his heart). God asked Pharaoh over and over again to let His people go. Pharaoh refused. The more God asked, and the stronger God’s plague warnings became, the more stubborn Pharaoh became and he had to make his heart harder and harder to resist God. So God was only hardening Pharaoh’s heart in the sense that Pharaoh had to harden his heart to resist God’s appeals. The same is true of the Jews. Through the centuries God sent prophet after prophet to Israel, and Israel suffered consequence after consequence because of their unbelief. The more prophets God sent, the more Israel hardened itself against them. So in the Semitic idiom, God is said to have hardened Israel’s heart, closed her ears, and blinded her eyes, and God’s asking Isaiah to make the people’s hearts fat was just God asking Isaiah to do what many prophets before him had done, which was to speak the prophetic word and thus make the people choose between doing what they wanted or doing what God wanted.

God’s people are still doing today what God told Isaiah to do 2,700 years ago. God tells Christians to “Preach the word; be ready at convenient times and at inconvenient times; reprove, rebuke, and exhort with all patience and teaching. For the time will come when they will not tolerate sound doctrine; but having itching ears, they will pile up teachers for themselves, to suit their own desires” (2 Tim. 4:2-3). God’s people teach the truth to people, but just as in Isaiah’s day, most people will choose their own desires over the Word and will of God. The more Christians preach the word, the more the people will harden themselves against it and defy God. If 2 Timothy had used the idiom of permission it might have been written this way: “Go harden the hearts of the people and close their ears and eyes to the truth.” How would Christians do that? Actually, they are doing it every day. By preaching, teaching, and witnessing, Christians are forcing people to openly make the choice between God’s desires and their own desires. Sadly, as Paul prophesied to Timothy, people will not tolerate the truth but will pile up teachers who teach what desire, what they want to hear.

Sadly, the history of the world is a history of people choosing their desires over God’s desires. Adam and Eve disobeyed God in the Garden of Eden. Cain disobeyed God and killed Abel. Pharaoh disobeyed God and would not let Israel go. Israel disobeyed God and chose pagan gods over God, and on through history the pattern goes. The language and idioms change, but God’s call to believers has not. Believers are still charged to speak the Word of God to people and “harden their hearts” by forcing them to openly and clearly make the decision to choose themselves over God.

[For more on the idiom of permission, see commentary on Romans 9:18. For a good example of the idiom of permission see commentary on Exodus 4:21. For more on why Christ taught in parables, see commentary on Matt. 13:13.]

“fat.” Here, “fat” is an idiom for insensitive, unreceptive, dull. Israel was “fat” when it came to the things of God. They were insensitive and unreceptive.