In the Garden of Eden, Satan came in the form of a serpent and the result was sin entered the world.
In the Exodus, Moses went before Pharaoh – the ruler of the world empire. When Aaron cast Moses’s staff before Pharaoh as God told Moses to do, it turned into a serpent – the symbol for sin. In return Pharaoh’s men cast their staffs down and their staffs also turned into serpents. But the serpent of God ate the serpents of Pharaoh. God’s symbol for sin took away the sins of the world. Aaron then lifted up the serpent and it turned back into a staff. But the serpents of Pharaoh were no more.
Later while wandering in the desert the Jews were complaining, so God sent fiery serpents to bite them and they were dying from being bitten. They asked Moses to pray to God then God told Moses to make a serpent of bronze and put it on a stick on a hill. Whenever anyone was bitten by a fiery serpent all they had to do was look at the bronze serpent and they would not die.
The only other mention of the bronze serpent is when Jesus sets up the most famous verse in the Bible.
John 3:14-18 “And as Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up, that whoever believes in Him should not perish but have eternal life.
For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life.
For God did not send His Son into the world to condemn the world, but that the world through Him might be saved. “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.”
Sin is not the issue.
Disbelief is the issue.