The great problem with trying to earn salvation is that no-one has ever done it! It is not that there was anything wrong with the Law. The problem is with human beings. In the movie the ‘Sound of Music’ a young woman by the name of Maria is sent from a convent to become governess to the five mischievous children of a wealthy widower sea captain. When she arrives Captain von Trapp informs her that the children have had seven governesses and that the last one had only lasted one day. Maria looked concerned and asks "What’s wrong with the children Captain?" The captain looks at Maria annoyed and says "there is nothing wrong with the children only with the governesses". The law of God is perfect. There is nothing wrong with it. The problem is really with us - the children of men. Our sinful nature makes us incapable of perfectly obeying God. As a result justification by perfect obedience to the law of God is a path that is completely closed to us.