Yet despite this, it was mercifully granted unto them that they might recognize their misdeeds, allowing them the chance to repent and obtain forgiveness.
Regarding John's assertion that they could not believe, as Isaiah had stated: “He has blinded their eyes and hardened their hearts, so they should not see with their eyes or understand with their hearts, nor be converted, and I should heal them” (John 12:39-40), it may appear to contradict the initial claim, urging us not to accept that it was said “let them never see with their eyes” or never discern even a single time. However, it is reasonable to acknowledge that it was explicitly asserted they should not see, as He clearly states—“that they should not see with their eyes.” Thus, He explains, “Therefore they could not believe.” He makes it abundantly clear that this blinding was not executed so that they, troubled by what they didn't grasp, would turn in repentance; for such a transformation couldn't occur unless they first believed. By believing, they could convert; through conversion, they would be healed; and through healing, they would come to realize. Rather, they were blinded by their disbelief, as He emphasizes repeatedly that they could not believe.
If this is indeed the case, who would defend the Jews by claiming they were not culpable simply because they could not believe? It was because they could not believe that He had blinded their eyes. Yet, in understanding God's nature as innocent, we must concede that they deserved this blinding due to their other sins, which in turn prevented them from believing. John's words convey this notion: “Therefore they could not believe, as Isaiah had said, that He had blinded their eyes” (John 12:39-40). It is futile to seek to interpret their blinding as a means for conversion since they could not convert due to their lack of belief, and consequently, they could not believe because they were blinded.
We could also state, without contradiction, that some of the Jews were indeed open to healing. However, they were so ensnared by pride that it was beneficial for them initially not to believe. To such a degree were they blind that they could not grasp the Lord speaking through parables; having failed to comprehend, they did not believe in Him. This lack of belief led them to crucify Him alongside others who were lost. Thus, after the Resurrection, they would have the opportunity to turn back, humiliated further by the judgment associated with the Lord’s death, and come to love Him who had forgiven them such a grave offense. Their pride was so profound that only a great humiliation could lead to their conversion.
It may appear improper to assert this unless one reads the Acts of the Apostles, where it aligns with John's claim: “Therefore they could not believe, because He had blinded their eyes, so that they should not see.” From this statement, we gather that they were blinded for the purpose of conversion—hidden from them were the Lord's teachings, expressed through the darkness of parables, so that following His Resurrection, they might repent more effectively. Not understanding the Lord’s message due to the obscurity of the preaching, they did not believe in Him, and because of their disbelief, they crucified Him. Therefore, upon witnessing the miracles done in His name after the Resurrection, they would be tormented by an even greater guilt for their transgression, leading to repentance, and ultimately receiving mercy for their obedience, with their love for Him rekindled.
As for those who were not aided by this blinding towards conversion, the prophet addresses them elsewhere— something also referenced by the apostle in discussions of the obscurity of tongues: “I will speak to this people in other tongues and with other lips, and so they will not hear me,” says the Lord (1 Cor. 14:21; Isaiah 28:11). It would not have been stated, “Thus they will not hear Me,” if it was not intended to strengthen them for humble confession, earnest searching, sincere conversion, and fervent love. The methodology of physical healing is similar; often, treatments initially inflict discomfort in order to heal. Ointments applied to the eyes, if necessary inside the eye, can only help if they first obscure sight, causing disturbance.
We need not be troubled that the prophet proclaims, “Unless you believe, you shall not understand” (Isa. 7:9), as this might appear to contradict John’s assertion that, “Therefore they could not believe, because He blinded their eyes” (cf. John 12:40). The former speaks to understanding profound truths in which He abides. However, when addressing what is to be believed, if one does not grasp what is expressed, it cannot be believed. Therefore, what is communicated must be understood to be believed, allowing for belief in that which has been spoken, while also necessitating belief in what has not been articulated for deeper understanding.