Hasn't pretty much the same argument been made against the understanding of God as an all powerful supernatural being and relegated to the realm of human projection - with the same moral argument that it only creates a moral scapegoat for all kind of inhumane actions throughout history? I sense that the New Atheism sees itself as a powerful moral force for good exactly on the basis of this kind of reasoning.  If the human misuse of mythological concepts and language determines what can or cannot be objectively real apart from the inner world our brains create, then why stop at Satan as a mere human invention?

If however the attempt to name a very powerful reality within the realm of our everyday experience at least served a legitimate purpose during the times of the New Testament church (for example in not seeing other human beings - "flesh and blood" - as the enemy) why can't it still serve the same kind of purpose for people today who feel no real benefit from an attempt of demythologizing for moral reasons at all? 

It seems to me that a big part of the Christian assurance all the way from the gathering of believers in Ephesus and Colossae in the first century to plagued consciences during the Reformation had as its bedrock the belief that Christ had utterly defeated all powers of evil and with it their inner voices of condemnation.