Before presenting the final teaching of Jesus to his disciples before his Arrest and Crucifixion, John presents his own comment on the unbelief of the Jews, their preferring of “darkness” to Light. Though technically his own comment, it is in reality but an expansion of what Jesus himself taught (see Mark 4:12; Matt. 13:14-15 & Luke 8:10).
Then to this comment (verses 37-43) on the origins of Jewish unbelief, John adds a concise statement by Jesus himself concerning the ultimate significance of his teaching and the ultimate destiny of those who reject it (verses 44-50).
Although the purpose of the signs or miracles of Jesus was not primarily to create faith in him but to confirm it, John reasons that their significance as public events was so overwhelmingly obvious that the unbelief of the Jewish people could only be explained in one way— as part of God’s providence and purpose in bringing salvation to the world. (Note the irony in the reference by John to signs, verse 37, and the comment by the Jewish authorities, chapter 11:47.) We recall that for St Paul, Jewish unbelief was also providential (Romans 11:11f.); but he also hoped that all Israel will be saved (11:26) even as John taught that Jesus will draw all men to himself (12:32).
In fact Jewish unbelief occurred, says John, so that ancient prophecy (Isaiah 51:1 & Isaiah 6:9-10) might be fulfilled. Those to whom “the arm of the Lord” had been revealed (in signs and wonders) had rejected the Messiah because their spiritual eyes were blind and their understanding darkened. And the latter though their own decision was at the deeper level of causation by divine intervention and providence.
In other words, the meaning of the prophecy of 6:10 for John is that the Christ (as the Logos) revealed to the prophet, Isaiah, that God would blind the eyes of the Jews, lest they should perceive the significance of his miracles, and He (Christ) would then of necessity heal them, and, thereby consequently obscure the judgment of God upon unbelief.
Of course, John was not writing out of a controversy on predestination and he was not intending to start a debate on predestination. His Gospel both emphasized the duty of each person who hears the Gospel to believe on the Son of God, even as here it fully acknowledges the role of the action of the sovereign God in the shocking unbelief of the Jewish people.
What John states in verse 41 is most important in terms of a Christian interpretation of the Old Testament: “Isaiah said these things because it was His glory that he saw, and about Him that he spoke.” In other words, the vision of Isaiah in the Temple, recorded in chapter six, is understood by John as a vision of the eternal Logos, the only-begotten Son. We recall his words in John 1:18, “No-one has ever seen God, the only-begotten who is at the Father’s side, he has made him known.” Therefore, John understands the ancient word of prophecy through Isaiah as speaking specifically to the situation in Jerusalem as Jesus, the Messiah and the Logos made flesh, approached his glorification via his sacrificial death on the Cross, a death which is also the salvation of the world and the healing of the nations.
Now John introduces a modification into the general statement that the Jews as a whole rejected Jesus as the Messiah. To a degree, some members of the Sanhedrin, the “rulers,” believed in him – Nicodemus (3:1ff.; 7:50f.; 19:39) and Joseph of Arimathea (19:38ff.). In fact the way that the trial of Jesus was conducted seems to suggest that his enemies were not sure that they had the whole Council against him. However, the secret disciples of Jesus were not open in their confession of belief for they feared the consequences in terms of their place in Jewish society and religion.
John does not bring his account of the rejection of Jesus as Messiah by the Jews to an end with a cold statement that mysteriously it was the fulfillment of prophecy (although it was such). He ends by declaring as clearly as possible using the words of Jesus what the rejection really was. It was ultimately the denial of God, the LORD, YHWH, the God of his elect people, the Jews; and it was so because Jesus, the Logos and Son, came from the Father and spoke and did what the Father commanded him. To reject him is to reject his Father, YHWH. And for this reason, the Jews must bear the consequences of this denial.
The relation of the perfect will of the sovereign God to the free will and decision of man, and vice versa, is wrapped in mystery and pursuing it in attempted depth is rarely profitable for godliness. The better way is to join St Paul in his doxology in Ephesians 1 and accept that the details of the perfect will of God, and how it operates in human lives, will never been known by us. In the case of the Jews in the time of Jesus, it is clear that they rejected him for their own reasons, clear and confused; but, at the same time, their unbelief and rejection were part of the plan of God for the redemption of the whole world. Just how this was so is known only in full by the Lord God himself, and before him we are to bow as his creatures and servants.