Now the serpent was more subtle than any beast of the field which the Lord God had made. In the early days of human history Satan tried to overthrow God's authority over the human race and replace it with his own.
Second thoughts hurt worse.
First Satan made Eve question God's word. God knows that when you eat of the fruit from this tree you will be like Him, knowing what is good and what is evil. The slyness of it. Adam and Eve already knew the difference between Good and Evil. They were perfect, and had all the benefits of the Preternatural gifts as well, including infused knowledge.