John 8:28, “When you have lifted up the Son of Man, then you will know that I am He…”
The window into the heart of ‘I AM’ opens widest at the cross.
When Jesus says that He’s the Light of the World in John 8:12, I think we are to understand that most primarily as Him being the one who communicates God to the world. Why do I say this? Because in John 1:4, we are told that the (eternal) life that has forever been in the Son is the “light” of mankind. So there we see eternal life and light linked.
Well, what is eternal life? Jesus defines that for us in John 17:3, it is to know the only true God and to know Jesus (which, as John 8:19 or 14:9 make clear, is not knowledge of two different beings, but to know Jesus rightly IS to know God). So, eternal life is to know God, and this knowledge of God–John 1:14 says–is the light of mankind / the light of the world.
This is why I say for Jesus to be the “Light of the World” means that He is the revelation of God to humanity. He is the one who communicates God to us. And in John 8:28, Jesus is saying that we will know Him most perfectly as this revelation of God when He is lifted up on the cross….that is where we will know that He is “I Am” (the “he” is added in English texts, the Greek simply says “εγώ ειμι” which is the wording that you’ll find in the Greek Old Testament’s recounting of Moses meeting YHWH at the burning bush (Exodus 3:14).
So–as I hope I will never tire of saying–if we want to know God, we look to His Son, and if we want to know the Son, we look most definitively to the climactic work of revelatory redemption: the crucifixion and resurrection of Jesus Christ.
