John 3:1-21 | What is a lesson for the original audience?

Fortunately for us, Jesus does an incredible job at explaining the exact lesson that He intends to be taken from this. Mankind needs to be born again and they are born again by putting faith in Jesus. The hearers of the day would have understood the reference that Jesus is making to Numbers 21. It is a modern issue that we forget that. So they would see what Jesus is really highlighting here. Sin is the serpent. Or rather, the pandemic of sin is the plague of the serpents. All who were bitten were destined to death. And why did this plague infect the people of Israel? They rose themselves against the Lord in their complaints. The loathed the worthless bread (manna) which Jesus relays in John 8 is Himself. They rejected God and were destined for death because of it. This is the same case for those stuck in sin. This is why they need to be born again. The trust in the Lord must be reinstated by looking upon that which is lifted up. In our case here, the type being fulfilled, we look unto Jesus.

What particularly stands out within the narrative is that it seems to imply quite clearly that there is actively a judgment already in place because of sin.

18 “He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God.
-John 3:18

In other words, you will maintain the judgment that is upon you should you not look upon the One who is lifted up. You are destined for death if you are not born again. The light has come. The darkness is being cast out.