The word “so” in John 3:16 means that Jesus would be lifted up like the bronze serpent in Numbers 21, become the embodiment of sin for us and die willingly with our sins blamed on Him as the sacrifice for our sins, so that whoever believes in Him will not perish but have everlasting life.
A statement of purpose can change a seemingly benign action into an insidious one or a bumbling mistake into the dear handiwork of a child. God’s statement of purpose in this text turns the injustice of the cross of Christ into a sublime, saving expression of His love. His purpose turns death to life, gives human existence on earth purpose instead of meaninglessness and changes our whole lives.