For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God.
John 3:16-18 (ESV)
John 3:16 is the story of story of:
The Greatest Danger: Our greatest danger is perishing, being condemned to eternal ruin, separated from the goodness of Christ after we die.
The Greatest Rescue: Our greatest rescue is by God who so loved the world, the world that was hostile to Him and that rebelled against Him, that He sent His only Son to die for our rebellion that we might not perish, but have eternal life.
The Greatest Promise: Our greatest promise is the that we can have eternal life and it can be our present possession that cannot be taken away.