21 Again he said to them, ‘I am going away, and you will search for me, but you will die in your sin. Where I am going, you cannot come.’ 22Then the Jews said, ‘Is he going to kill himself? Is that what he means by saying, “Where I am going, you cannot come”?’ 23He said to them, ‘You are from below, I am from above; you are of this world, I am not of this world. 24I told you that you would die in your sins, for you will die in your sins unless you believe that I am he.’* 25They said to him, ‘Who are you?’ Jesus said to them, ‘Why do I speak to you at all?* 26I have much to say about you and much to condemn; but the one who sent me is true, and I declare to the world what I have heard from him.’ 27They did not understand that he was speaking to them about the Father. 28So Jesus said, ‘When you have lifted up the Son of Man, then you will realize that I am he,* and that I do nothing on my own, but I speak these things as the Father instructed me. 29And the one who sent me is with me; he has not left me alone, for I always do what is pleasing to him.’ 30As he was saying these things, many believed in him.
“Again he said to them” – the teaching that follows is a repetition of 7:34. Repetition is always significant when we are reading Scripture. The author had something to say that bears repeating! But it can also be helpful to look at what is bracketed by the repetition, and what follows each one. The words in this case bracket, and are followed by, the ongoing controversy with the Pharisees and religious leaders at the Festival of Booths. The first time he said this, his audience thought he meant he was going among the Greeks to teach them; now they think he is going to kill himself. (Suicide was a serious offense to the Jews; this is not a generous assumption.) But Jesus tells them that he is not of this world, though they are; he is from above.
Jesus tells them that they will die in their sins unless they believe “I am he”, which should be read “I AM”, connecting Jesus to the divine name of God, YHWH. Forgiveness and grace are from God, through Jesus, as he says here (v.28). But his opponents still do not understand, are still thinking at the surface of what he is saying, and respond, “Who are you?” By then he is disgusted – “Why do I speak to you at all?” He could condemn them, but he speaks only what the Father has sent him to declare. Still they do not understand.
And Jesus says, “When you have lifted up the Son of Man, then you will realize that I am He.” “And the One who sent me is with me; he has not left me alone.” He is speaking of the crucifixion, and resurrection. When they have crucified him, and on the third day he has risen, then they will understand that he is from God, God’s Son, and that God is with him, even on the cross and in the tomb.
And “as he was saying these things, many believed in him.” Of course those who believed were not those religious leaders who opposed him, but people from “the crowd”, who were finally catching on, seeing beneath the surface – seeing with spiritual eyes.