That's an interesting song, alright. The struggle between the spiritual and humanist elements in Christianity has gone on since the beginning. Since Christ's emphasis was on spiritual salvation, He was likely looked upon as a disappointment by those who sought a leader in the attempt to overthrow Roman rule. The fact that Christ was also pragmatic is often overlooked. I believe that He realized that the Zealots had a snowball's chance in Hell of overthrowing the Romans. Thus the statement "render unto Caesar what is Caesar's" is only at face value a renunciation of earthly power and the will to struggle: It is basically a message to His followers that violent revolution against the most powerful occupying army the world had ever seen was futile. The key had to lie in a basic sea-change in man's behavior and beliefs. The fact that eventually this Great Empire would adopt belief in Him as its official religion was something which even Christ may not have foreseen.