When Jack Kirby designed the Silver Surfer, He looked towards the bible as inspiration. The Villain Galactus represents the spiritual cosmic force that we all feel (in other words God). The Silver Surfer represented the fallen angel that betrays the natural force for his own selfish love of humanity. For his actions he is rejected and forced to stay on earth (Similiar to the story of Lucifer the fallen angel). The Color silver also represents the string that connects the human body to the soul.