ISB ~ John 3 v6

flesh … spirit:A significant contrast in John. Flesh represents all that is natural, earthly, and human, while spirit signifies all that is supernatural, heavenly, and divine. The distance once separating these realms has been bridged by Jesus Christ, whose flesh (1:14) is an instrument that conveys the life and Spirit of God to the world (5:21; 6:51-53; 20:22).