Nevertheless, the concept of divine hardening plays an extremely prominent role in the NT. The passage from Isaiah 6.9-10 quoted in John 12.40 is repeated in Matthew 13.13-15, Mark 4.11-12, Luke 8.10, and Acts 28.25-27, making it one of the most commonly cited passages in the NT. Furthermore, a similar passage from Isaiah 29.10 is quoted by Paul in Romans 11.7-8. Clearly, the writers of Scripture are not embarrassed by the concept of divine hardening, nor do they consider it an obscure or unimportant doctrine. Rather, it plays a significant role in their theology.
How then are we to understand this doctrine?
Before we can understand what the NT authors are saying, we must first understand what Isaiah was saying. However, in order to understand Isaiah, we must go all the way back to one of the most significant chapters in the OT: Deuteronomy 28.
In Deuteronomy 28, God outlines the blessings and cursings of the covenant. In other words, he tells Israel precisely what will happen to them if they continue in his covenant, and precisely what will happen to them if they transgress his covenant. If they are obedient, they will receive abundant rain, bountiful harvests, and political peace, but if they are disobedient, they will experience famine, plague, and ultimately exile. Deuteronomy 28, therefore, can be considered the “plot spoiler” of the OT. Once you read Deuteronomy 28, you know exactly what is going to happen in the rest of the story.
One of the curses outlined in Deuteronomy 28 is blindness and confusion:
But it shall come to pass, if you do not obey the voice of the Lord your God, to observe carefully all His commandments and His statutes which I command you today, that all these curses will come upon you and overtake you…The Lord will strike you with madness and blindness and confusion of heart. And you shall grope at noonday, as a blind man gropes in darkness. (Deut. 28.15, 28-29)
The divine hardening of Isaiah 6.9-10, therefore, is not some arbitrary decision God has made, but rather a fulfillment of the punishment he outlined in Deuteronomy 28. The fact that divine hardening is a punishment for prior rejection is made explicit later on in Isaiah 29:
They are drunk, but not with wine; they stagger, but not with intoxicating drink. For the Lord has poured out on you the spirit of deep sleep, and has closed your eyes, namely, the prophets; and He has covered your heads, namely, the seers….Therefore the Lord said: “Inasmuch as these people draw near with their mouths and honor Me with their lips, but have removed their hearts far from Me, and their fear toward Me is taught by the commandment of men, therefore, behold, I will again do a marvelous work among this people, a marvelous work and a wonder; for the wisdom of their wise men shall perish, and the understanding of their prudent men shall be hidden.” (Isaiah 29.9-14)
Up to this point, therefore, we have shown that divine hardening is not to be understood as a reflection of any unfairness or unkindness in God. God is simply judging sinners for their sin. However, there is more to be said. Far from demonstrating any unfairness or unkindness in God, divine hardening actually reveals the amazing extent of his grace and love!
Isaiah 6 marks a significant turning point in the OT narrative. Up until this point, Israel has been stuck in a never-ending cycle, particularly apparent in the book of Judges: sin, punishment, repentance, deliverance, sin, punishment, repentance, deliverance, sin, etc. The periods of judgment were intended to produce a lasting and genuine repentance, but they did not (see Amos 4.6-11).
Through divine hardening, however, God prevents the people from repenting and being delivered. Thus he cuts the cycle off and forces the people to experience the full extent of judgment, “Until the cities are laid waste and without inhabitant, the houses are without a man, the land is utterly desolate” (Is. 6.11). But here is the important point: he does this so that the people will realize the depths of their sin and be driven to a deeper and more permanent repentance.
Now it shall come to pass, when all these things come upon you, the blessing and the curse which I have set before you, and you call them to mind among all the nations where the Lord your God drives you, and you return to the Lord your God and obey His voice, according to all that I command you today, you and your children, with all your heart and with all your soul, that the Lord your God will bring you back from captivity, and have compassion on you, and gather you again from all the nations where the Lord your God has scattered you....And the Lord your God will circumcise your heart and the heart of your descendants, to love the Lord your God with all your heart and with all your soul, that you may live. (Deut 30.1-6)
In the NT, Paul realizes that God’s same plan is still at work. In what I find to be one of the most wonderful and surprising passages in all of Scripture, Paul explains that the punishment of divine hardening is actually intended to bring all Israel to salvation:
I say then, have they stumbled that they should fall? Certainly not! But through their fall, to provoke them to jealousy, salvation has come to the Gentiles…For I do not desire, brethren, that you should be ignorant of this mystery, lest you should be wise in your own opinion, that blindness in part has happened to Israel until the fullness of the Gentiles has come in. And so all Israel will be saved. (Rom. 11.11, 25-26)
As Paul summarizes,
For God has committed them all to disobedience, that He might have mercy on all. Oh, the depth of the riches both of the wisdom and knowledge of God! How unsearchable are His judgments and His ways past finding out! (Rom. 11.32-33)