What does it mean that God hardened their hearts (John 12:40)?

John, however, views their conduct in a stage subsequent, as it were, to their wilfulness. Having hardened their own hearts, their hearts are there-upon hardened penally. They would not believe, therefore they could not believe. John's words are emphatic that a judicial infliction from God had fallen upon the people. He says, "For this cause they could not believe, for that Isaiah said, He has blinded their eyes, and hardened their heart, lest they should see with their eyes and perceive with their heart, and should turn, and I should heal them" (John 12:39-40). This quotation is made from the Hebrew text of Isaiah, where the ultimate result of unbelief upon the nation is the prominent theme.

It will be observed that only a part of the original prophecy is quoted in the Fourth Gospel, and that the clause relating to their hearing is not included. From the context we see that the Evangelist is speaking of the signs of Jesus rather than of His teaching (ver. 37), and His miracles were for the eyes of the people while His doctrine was for their ears. John brings forward therefore only the clauses referring to their eyes and heart, which God had blinded and hardened because of their stubborn opposition to the gospel of the kingdom. But the principle of judicial penalty is equally applicable to the ear, as the actual form of the prophecy of Isaiah shows.

And it may also be helpful in this connection to mark that this order is invariably observed in scripture. It is not till man's will actively opposes God's that He manifests His sovereignty. It is when man will not that he cannot. This is shown clearly enough in this Gospel (John); and, in direct sequence to the scripture before us, we read "But though He had done so many miracles before them, yet they believed not on Him; that the saying of Esaias the prophet might be fulfilled which he spake, Lord, who has believed our report? and to whom has the arm of the Lord been revealed"? (John 12:37-38). Plainly they would not believe (John 5:40), though ample proofs were afforded. Then the passage proceeds, "Therefore they could not believe, because that Esaias said again, He has blinded their eyes and hardened their heart; that they should not see with their eyes nor understand with their heart and he converted and I should heal them. These things said Esaias when he saw His glory and spake of Him" (John. 12:39-41) So that we see they could not believe because they would not. However this hardening was but national and was not apart from mercy; for it is immediately added "Nevertheless among the chief rulers also many believed on Him"

But as the first citation proves the guilt of rejecting God's testimony, so the second, though really earlier, points to the solemn fact of judicial blindness, never pronounced, still less executed, of God, till patience has had its perfect work and man has filled up the measure of his guilt beyond measure. Under such a sentence of hardening, no doubt, they could not believe;240 but the sentence came because of wickedness consummated in wilful rejection of God and His will when they did not believe, in spite of the fullest appeals to their hearts and consciences. As the first citation shows utter unbelief when Christ came in humiliation and suffering to do the work of atonement, so the latter conveys the dread word which shut them up in blindness before the light they had so long despised, followed up by the inspired comment that these things said Isaiah when he saw Christ's glory and spoke of Him.241 It is Jehovah in the prophecy, Christ in the Gospel; but they are one — as, indeed, Acts 28:25-27 enables us to include the Holy Spirit. How thoroughly confirmed and confirming the still older oracle in Deut. 6:4, "Jehovah our God is one Jehovah!" John 12: and Acts 28 weaken it in nothing, but add to its force and expressiveness, as they show out more and more the patience of God and the darkness of the Jew after ages of trifling with His mercy and His menaces alike. And the darkness increased as the light shone out.

John 12:39-41. Secondly, seeing they would not believe, the time came when "they could not believe". They became judicially hardened. Isaiah, who prophesied of their deliberate rejection, also foretells the judicial judgment that is the outcome of the rejection of Christ. They had steeled their hearts against His words and closed their eyes to His works of power. As a result God gave them up to the blindness and hardness that they themselves had chosen.

Solemn is the divine comment that His many miracles did not persuade them to believe Him personally, as Isaiah 53:1 had prophesied. No doubt many knew this prophecy, but blindly fulfilled it in refusing Him. More solemnly still we are told “they could not believe,” because God had blinded their eyes and hardened their heart. (vv. 39-40). But we must not suppose that God did this without reason. Just as Pharaoh first hardened his own heart against God before we read of God's hardening his heart (Ex. 5:1-2; Ex. 7:3), so when the Jews hardened themselves against the Lord Jesus, then God confirmed their blindness by His judicially blinding them. Let men dare to go too far in opposition to God, and this may be the awful result.

But the majority of the people had not believed and v. 39 introduces the second quotation from Isaiah, "This is the reason for which they did not believe". "He has blinded their eyes, and hardened their heart: that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them" (John 12:40 — See Isaiah 6:10). This is a "hard saying". Who can hear it? But its hardness arises from the slowness with which we see things from God's point of view. It was God who sent Jesus, foreshadowed by Jehovah's sending Isaiah. He was the initiating actor. If God sends light to those who are firmly set against receiving it, then the coming of that light is the occasion of hardening them, as in the case of Pharaoh (Exodus 4:21, 8:15 and 32, 9:34 so applied in Romans 9:18). The rulers in Jerusalem, against all miraculous signs, against all Scripture, against the full evidence outlined in John 5;32-47, had indeed manifested hearts incorrigibly set against believing; and thus the coming of the light hardened hearts set to refuse the Sent One. The process can be traced. Every fresh sign produced, not conviction and faith, but a hardening intention to silence in death the voice of the Sent One. In John 5:16 the Jews sought to slay Him because He had broken the Sabbath. The blinding flash of divine light in the miracle of healing, they saw not; they saw only the breaking of their tradition. Further light, in the Lord's showing that God was His Father and how He was one with God, simply hardened their line — v. 18 "they sought the more to kill Him". Thus the process of hardening can be traced, until His hour was come (John 12:23, 13:1, 17:1).

John also quotes Isaiah's prediction, but in a different connection. It is cited at a later stage in the history of Israel's opposition to their Messiah. Though Jesus did so many signs before them yet they believed not. And since they would not believe, it came to pass that they could not believe. And the Evangelist brings forward the ancient oracle which warned of this blindness which came as a divine judgment upon the nation. "For this cause they could not believe, for that Isaiah said, He has blinded their eyes and he hardened their heart, lest they should see with their eyes, and perceive with their heart, and should turn, and I should heal them" (John 12:37-40). This quotation, it will be observed, is from the Hebrew text, and is introduced historically immediately before the final act of unbelief the crucifixion of Christ. The truth was there hidden from their eyes, even the eyes of the wise and prudent (Matt. 11:25; Luke 19:42).

Thus we see that the prophecy is quoted in the Synoptical Gospels and in the Acts to show that the blindness of Israel was due to their own wilful obstinacy, and in the Gospel of John to show that it was the result of the judgment of God. Both aspects are of course true and necessary to a complete presentation of the truth.

A summary of the situation up to this point is furnished by the Evangelist in verses 37-43. Jesus had done many signs before them, yet they did not believe on Him. The fact was this: their eyes were blinded. The blinding of the eyes of men is the work of the god of this age, as we learn from 2 Corinthians 4:4. Yet there are times when God specially permits it to take place in governmental retribution, and so it can be attributed to Him. Such was the case here; such it had been in the days of Isaiah; and such it was again some 35 years later, when the testimony to the glorified Christ was refused (see Acts 28:25-27). The unbelieving generation persists, and will still be found when the final judgment falls at the end of the age.

But we must remember it is in relation to the things of Christianity that He has blinded them judicially, not to the things He promised them in the prophets. Read a little higher up in John 12:37, "yet they believed not". It was after they had refused Christ as their Messiah that God closed their eyes to the greater things the Son was bringing to pass. So it is in this chapter. We must see that God is righteous in His dealings. They closed their eyes themselves to that which was so obviously outlined in their prophetic word, therefore God judicially closed their eyes to that which was not obvious and which came to light in the ministry of our Lord. He said to them in another place, "For had ye believed Moses, ye would have believed Me" (John 5:46).