Milton's theme in Paradise Lost, however, does not end with the idea of disobedience. Milton says that he will also "assert Eternal Providence." If Man had never disobeyed God, death would never have entered the world and Man would have become a kind of lesser angel. Because Adam and Eve gave in to temptation and disobeyed God, they provided the opportunity for God to show love, mercy, and grace so that ultimately the fall produces a greater good than would have happened otherwise. This is the argument about the fall called felix culpa or "happy fault."
The general reasoning is that God created Man after the rebellion of Satan. His stated purpose is to show Satan that the rebellious angels will not be missed, that God can create new beings as he sees fit. God gives Man a free will, but at the same time, God being God, knows what Man will do because of free will. Over and over in Paradise Lost, God says that Man has free will, that God knows Man will yield to Satan's temptation, but that he (God) is not the cause of that yielding; He simply knows that it will occur.
This point is theologically tricky. In many ways, it makes God seem like a cosmic prig. He knows what Man will do, but he does nothing to stop him because somehow that would be against the rules. He could send Raphael with a more explicit warning; he could tell Gabriel and the other guards where Satan will enter Eden; he could seal Satan up in Hell immediately. He could do a number of things to prevent the fall, but he does nothing.
From the standpoint of fictional drama, a reader may be correct in faulting God for the fall of Adam and Eve. From a theological / philosophical standpoint, God must not act. If Man truly has free will, he must be allowed to exercise it. Because of free will then, Adam and Eve disobey God and pervert the natural hierarchy. Death is the result, and Death could be the end of the story if Paradise Lost were a tragedy.
