Isaiah 6 is a chapter well known to many. In it we read of Isaiah's experience of being in the presence of the Lord.
In the year of King Uzziah's death I saw the Lord sitting on a throne, lofty and exalted, with the train of His robe filling the temple. Seraphim stood above Him, each having six wings: with two he covered his face, and with two he covered his feet, and with two he flew. And one called out to another and said, "Holy, Holy, Holy, is the LORD of hosts, the whole earth is full of His glory." and the foundations of the thresholds trembled at the voice of him who called out, while the temple was filling with smoke.
Then I said, "Woe is me, for I am ruined! Because I am a man of unclean lips, and I live among a people of unclean lips; for my eyes have seen the King, the LORD of hosts (Isaiah 6:1-5 NASB).
There is no doubt that Isaiah saw God. The Hebrew word translated LORD is Yehovah, the self existing, eternal one. What Isaiah saw was an awesome manifestaion of the glory of the LORD, while Seraphim cried "Holy, holy, holy," and the temple shook. In fact Isaiah was undone in the presence of Yehovah God.
As we read on we see that one of the Seraphim flew toward him with a coal from the altar, and touched his lips, purging his sin, and taking away his iniquity (Isaiah 6:6-7).
In John's gospel we read of the final events of Jesus' ministry in the days leading up to His arrest and crucifixion. John 12:38 tells us that in spite of all the signs that He had performed before the people, they did not believe in Him. This was to fulfill the word of Isaiah the prophet which he spoke: "LORD, WHO HAS BELIEVED OUR REPORT? AND TO WHOM HAS THE ARM OF THE LORD BEEN REVEALED (John 12:38 NASB)?
In spite of three years of ministry, teaching, and miracles of every kind, the people in general rejected Jesus as their Messiah, as the very Son of God. In describing the manner of death by which He was to die, the people asked, "Who is this Son of Man?" They were confused by His use of this divine title (Daniel 7:13-14), believing that the Messiah was to remain forever (John 12:32-34).
All this was a fulfillment of Isaiah 53:1. Jesus, the Arm of the LORD had been revealed to Israel, as Yehovah God, their God and king, the God of Abraham, Isaac, and Jacob, yet they did not believe. Isaiah 53 continues on to show the events that were yet to come in the life of Jesus. It speaks of the horror and injustice of his arrest, torture and death. However it also shows us why. He suffered all of this as a sacrifice for sin; to bear the iniquity of mankind so that we could be reconciled to God. And the unbelief of the people played into this as the events unfolded.
John also quotes Isaiah 6:9-10 to show that the unbelief of the Jews fulfilled prophecy,
For this reason they could not believe, for Isaiah said again, "HE HAS BLINDED THEIR EYES AND HE HARDENED THEIR HEART, SO THAT THEY WOULD NOT SEE WITH THEIR EYES AND PERCEIVE WITH THEIR HEART, AND BE CONVERTED AND I HEAL THEM."
These things Isaiah said because he saw His glory, and he spoke of Him (John 12:39-41 NASB).
Whose glory did Isaiah see? and who was Isaiah speaking of? John is showing us that the words of Isaiah were being fulfilled before their very eyes. Isaiah had prophesied of this. It was Jesus whose glory that he saw. Jesus was the LORD high and lifted up, seated on the throne, and it was Jesus whom Isaiah spoke of. Jesus the "Word become flesh, who is the image of the invisible God, in whom all the fullness of God dwells in bodily form (John 1:14, 12:44-45, Col 1:15, 19).