It was part of God's plan. He knew that Satan would tempt A&E, and he knew that they would submit to this temptation. But man also needed to be made mortal and gain wisdom, so that we would have free will, and God knew this as well. He knew that because of this original sin, we would all be sinners, which is why he then gave his son to die for our sins. He did not set A&E up as a cruel trick, he did it because it was necessary, and because of Christ, even A&E have the chance to repent. And Because of A&E, we all have the opportunity to prove our worthiness to God.