John 8:21-30 (ESVST)
So he said to them again, “ I am going away, and you will seek me, and you will die in your sin. Where I am going, you cannot come.”
Jesus is still in Judea at the temple. The feast of booth has ended and Jesus was preaching to those who were there. He had just told them that he is the light of the world. The above verse starts by saying “So he said to them again,”, this is as I have just sated that he had just finished telling them that he was the light of the world. Jesus again told them that he was going away to heaven and they will look for him and those who did not believe in him, will die in their sins. Jesus told them that where he is going they cannot come. They cannot come because he is going to heaven and in heaven, only those that believe may enter.
22 So the Jews said, “Will he kill himself, since he says, ‘ Where I am going, you cannot come ’?” 23 He said to them, “ You are from below; I am from above. You are of this world; I am not of this world.
Jesus still emphasizes the fact that they cannot go where he is going because he is from above and they are from below. They are of this world ruled by the devil and he is not of this world. Where he is going, since they are of this world, they cannot come.
24 I told you that you would die in your sins, for unless you believe that I am he you will die in your sins.” 25 So they said to him, “ Who are you?” Jesus said to them, “ Just what I have been telling you from the beginning.
Jesus then again speaks about the fact that where he is going they cannot come by saying that he told them this because unless they believe and obviously believe in him, that he is the Son of God, God reincarnate, they will die of their sins. They still did not understand what Jesus was talking about, showing again a lot of ignorance when it came to scriptures. Jesus then says, I have been telling you exactly that from the beginning and you are not listening and if you do listen, you refuse to believe.
26 I have much to say about you and much to judge, but he who sent me is true, and I declare to the world what I have heard from him.” 27 They did not understand that he had been speaking to them about the Father.
Jesus then told them that he has so much to say about them and lot to condemn but for now, he will only say what God who sent him wants him to say and that God is truthful. Again they failed to understand that he was talking about God. John here is simply trying to highlight that their unbelief is based on nothing but ignorance of scripture.
28 So Jesus said to them, “ When you have lifted up the Son of Man, then you will know that I am he, and that I do nothing on my own authority, but speak just as the Father taught me. 29 And he who sent me is with me. He has not left me alone, for I always do the things that are pleasing to him.” 30 As he was saying these things, many believed in him.
Jesus then told them that when you have killed me, the Son of Man, and after I have been lifted up into heaven, only then will you realize that I am indeed the Son of God the Christ that you have been promised. Notice that Jesus does not say when I am lifted up but he says when you have lifted me up, meaning when they have crucified him.
You will also know that I was sent by God and had only spoken what I was taught by God to say. I did nothing of my own authority. Jesus continued to tell them that God is always with him and has not left him because he always does what is pleasing to God.
As he was saying these things, John says, many believed in him.