"then the law of the jungle and survival of the fittest is the supreme law."
A quick thought on this  ultimate mysterious question of how and why and  by whom we were created-- Paul, I like your letter and I guess that's how I saw the world back in Sunday School.  
But I 'd take issue with your belief that without faith in a creator we have only the law of the jungle.  While we humans tend to be born self-centered and tribalistic, we also have the potential of experiencing joy with the happiness of others and feel good when we do something for someone.  Using our minds we figure out that if each of us "follows the rules" in a goodnatured fashion, we'll all end up happier than when, like when we were younger, we just automatically grabbed for what we could get away with.  While Social Darwinism sounds great in theory it often ends in destruction.
As a result all societies create rules on how to behave, but too often it's those with the power who write the rules to control others.