What does the phrase “light of the world” mean? John 8:12: “Jesus spoke to them, saying, ‘I am the light of the world.’” What does “of the world” mean? The whole world is not being lightened while Jesus is there, or today. You can see it right there in the text — you don’t need experience only. Jesus continues to say, “Whoever follows me will not walk in darkness.” That is, if we don’t follow him, we do walk in darkness, which means there is darkness in the world.
If you follow Jesus, you won’t walk in darkness. If you don’t follow Jesus, you walk in darkness. So it’s there. What then does “light of the world” mean if the darkness is there, and Jesus hasn’t yet taken it away? This is what I think it means. I’ll give four meanings that I think are true.
First, Jesus’s being “the light of the world” means the world has no other light than him. If there is going to be light in the world, it will be Jesus. It is Jesus or darkness. There is no third alternative. No other light. So he’s the light of the world in that there is no other light in the world. There is only darkness.
Second, it means, therefore, all the world, and everyone in it, needs Jesus as their light, because they are in darkness without him. Everybody needs Jesus as the light. There isn’t any other light.
Third, it means that the world was made for this light. “Light of the world” means that God made the world for this light. Creation was made for this light to fill it. This is not a foreign light to this world. This is the light of the owner of the world. When this light comes, it not only makes sin plain as foreign and ugly to what God has made, but it also enables us to see everything good in its true light. Without the light of Jesus, you don’t see anything the way you should see it.
The light of Jesus illumines everything with its proper beauty. Without the light of Jesus in our hearts, enabling us to see the world that was made for the light, we can’t see the world the way it is in God’s eyes. Everything is dark. This world was made to be illumined by this light. The light of Christ is native to the world, not foreign.
Fourth, one day this world will be filled with the light of Jesus — and nothing else. When this light comes, it not only makes sin plain, but sooner or later it will take all darkness and banish it out of the world. This includes the works of darkness and the sons of darkness. This is why Jesus called hell “outer darkness” (Matthew 8:12; 22:13; 25:30).
There will be no darkness in the world or in the universe. Hell is utterly outside of the creation God has made, being in its unique place. And it’s dark — totally dark. Don’t get bent out of shape with fire without light. That’s not a problem for God. There are more horrors of hell than you ever dreamed of — darkness, utter darkness, and you don’t know where the next blow is coming from.
Jesus is the radiance of the Father, and he will fill the world and everything in it with light. Jesus is the light of the world.
Source: John Piper | Desiring God