he that believeth not is condemned already

John 3:18 is what I call an A and B verse. John 3:16 is an example of an implied verse.
John 3:16 For God so loved the world that He gave His Only Begotten Son, that whosoever believeth in Him should not perish but have everlasting life.
part B) is implied. If you do not believe you will have everlasting Death.

These verses are written in Red, God says them, they have His full authority in them.