At John 12:39 the apostle quotes Isaiah’s prophecy in connection with Jesus’ work and then adds: “Isaiah said these things because he saw his glory, and he spoke about him.” (NW) The trinitarian clergy say that this proves the doctrine of the trinity and that the Jehovah whom Isaiah saw in glory in the temple was the prehuman Jesus, the Word of God. But this is a hasty conclusion on their part, as appears from John’s full account, which we here quote: “Jesus spoke these things and went off and hid from them. But although he had performed so many signs before them, they were not putting faith in him, so that the word of Isaiah [53:1] the prophet was fulfilled which he said: ‘Jehovah, who has believed our report, and to whom has the arm of Jehovah been revealed?’ The reason why they were not able to believe is that again Isaiah [6:10] said: ‘He has blinded their eyes and he has made their hearts hard, that they should not see with their eyes and get the thought with their hearts and turn around and I should heal them.’ Isaiah said these things because he saw his glory, and he spoke about him.”—John 12:36-41, NW.
What “things” did Isaiah say “because he saw his glory”? Well, John quotes Isaiah here twice, first quoting Isaiah 53:1 concerning the “arm of Jehovah” and then quoting Isaiah 6:10 concerning the temple vision. At Isaiah 53:1 the “arm of Jehovah” is Christ Jesus. At Isaiah 6:10 the speaker at the temple is Jehovah, but he includes his Son with him when he says: “Who will go for us?” that is, for me and my Son. Thus we see that the prehuman Jesus was associated with Jehovah in his glory at the temple, and hence John could rightly say Isaiah here saw his glory and spoke about him, “the arm of Jehovah.” Certainly Jesus the Greater Isaiah had not sent himself, but Jehovah at the temple did so, for John here applies Isaiah 6:10 to Jesus as the Sent One toward whom this prophecy was first fulfilled, after Jesus had ridden into Jerusalem and offered himself as King and had cleansed the temple. At that time Jesus was not in “his glory”, but the Jewish leaders had vilified him and had conspired to kill him.
The same was true where Matthew 13:14, 15 applies Isaiah’s prophecy to Jesus, for there, too, the religious leaders had formed a conspiracy to destroy him. (Matt. 12:14; John 11:57) The glory of Jesus with his Father at the temple comes at the final and complete fulfillment of Malachi 3:1-4 in the year 1918, when Jehovah sends him as his Messenger of the covenant to judge and purify His consecrated people. Especially since his resurrection, Jesus is the reflection of Jehovah’s glory.—Heb. 1:2, 3; 2 Cor. 4:6. Also see page 215, ¶ 4.