John 12:37

Here he expressly foretells the opposition of the Jews to him and how they will see him and not understand who he is. He foretells how they will hear him speaking and teaching them but will be quite unable to grasp who it is that speaks with them or the new teaching he offers them. And John the Evangelist witnesses to the fulfillment of these words referring to our Savior where he says, "Though he had done so many signs before them, yet they believed not on him, that Isaiah the prophet's words might be fulfilled which he spoke, 'Lord, who has believed our report, and to whom has the arm of the Lord been revealed?' Therefore they were not able to believe, because again Isaiah said, 'He has blinded their eyes and hardened their heart, so that they should not see with their eyes, and understand with their heart and be converted, and I should heal them.' Isaiah said these things when he saw his glory and bore witness of him." Thus the Evangelist most certainly referred the theophany in Isaiah to Christ and to the Jews who did not receive the Lord that was seen by the prophet, according to the prediction about him.

(Hom. lxviii. 1) And thus the Evangelist tacitly explains it, when he adds, But though He had done so many miracles before them, yet they believed not on Him.

(Tr. liii. 2) But some mutter, and ask, What fault was it of the Jews, if it was necessary that the sayings of Esaias should be fulfilled? We answer, that God, foreseeing the future, predicted by the Prophet the unbelief of the Jews, but did not cause it. God does not compel men to sin, because He knows they will sin. He foreknows their sins, not His own. The Jews committed the sin, which He who knows all things foretold they would commit.

There are some, then, who mutter among themselves, and sometimes speak out when they can, and even break forth into turbulent debate, saying: What did the Jews do, or what fault was it of theirs, if it was a necessity "that the saying of Isaiah the prophet should be fulfilled, which he spake, Lord, who hath believed our report and to whom hath the arm of the Lord been revealed?" To whom our answer is, that the Lord, in His foreknowledge of the future, foretold by the prophet the unbelief of the Jews; He foretold it, but did not cause it. For God does not compel any one to sin simply because He knows already the future sins of men. For He foreknew sins that were theirs, not His own; sins that were referable to no one else, but to their own selves. Accordingly, if what He foreknew as theirs is not really theirs, then had He no true foreknowledge: but as His foreknowledge is infallible, it is doubtless no one else, but they themselves, whose sinfulness God foreknew, that are the sinners. The Jews, therefore, committed sin, with no compulsion to do so on His part, to whom sin is an object of displeasure; but He foretold their committing of it, because nothing is concealed from His knowledge. And accordingly, had they wished to do good instead of evil, they would not have been hindered; but in this which they were to do they were foreseen of Him who knows what every man will do, and what He is yet to render unto such an one according to his work.

And the Evangelist, wishing to convict their immoderate stubbornness, adds also the words: before them; showing that they did not believe even what they saw.

He means the miracles related above. It was no small wickedness to disbelieve against such miracles as those.

That they did not believe but were vexed, the Evangelist himself indicated when he said, "Though He had done so many miracles, they did not believe in Him." And of course it is a matter of no small malice not to believe so many miracles. "So many," he says, "miracles about which he [the Evangelist] kept silent."
So. Jesus hid Himself in order to calm their malice, and at the same time in order to give them time and tranquility so that, having calmed down, they might consider His words and deeds. For in that case, if they had wished, they could have come to an understanding of His dignity — His Divinity. Although He knew their unbelief in advance, nevertheless, what depended on Himself, He did and permitted, giving them, as has been said, time for consideration.

Although he had done so many signs before them, they did not believe in him: such as the sign of the raising of Lazarus: yet they did not believe, because their malice did not permit it: Wisdom 2: "Their malice blinded them." Nor did this happen by chance, but it was foreseen by the Lord and foretold through the Prophet Isaiah.

Above, the Evangelist gave many examples of Christ's glory, because of which the Jews sought to kill him out of envy. Now he deals with another of the occasions surrounding his passion, that is, the unbelief of the Jews. First, their unbelief is discussed; in the second place, it is reproved by our Lord (v 44). Concerning the first he does two things: first, he reproves the unbelief of those who did not believe at all; secondly, the unbelief of those who believed, but in secret (v 42). As to the first, two things are done: first, he mentions the strange hardness of their unbelief; secondly, to show that it came about not without reason or by chance, he mentions a prophecy (v 38).

The Evangelist, as though at a loss to explain it, says that our Lord had done many miracles: such as changing water into wine, curing a paralytic, giving sight to a blind man, and raising a dead man to life: nevertheless, though he had done so many signs before them, yet they did not believe in him. They usually said: "What sign do you do, that we may see, and believe you?" (6:30). But now! The Evangelist says: though he had done so many signs before them, yet they did not believe in him. "If I had not done among them the works which no one else did, they would not have sin" (15:24). And so they could not say: "We do not see our signs" (Ps 74:9).