Continuing with the discussion of the fall, Calvin writes:
It is now asked, What was the sin of both of them? The opinion of some of the ancients, that they were allured by intemperance of appetite, is puerile. For when there was such an abundance of the choicest fruits what daintiness could there be about one particular kind? Augustine is more correct, who says, that pride was the beginning of all evils, and that by pride the human race was ruined. Yet a fuller definition of the sin may be drawn from the kind of temptation which Moses describes. For first the woman is led away from the word of God by the wiles of Satan, through unbelief…
Therefore, unbelief was the root of defection; just as faith alone unites us to God. Hence flowed ambition and pride, so that the woman first, and then her husband, desired to exalt themselves against God. For truly they did exalt themselves against God, when, honor having been divinely conferred upon them, they not contented with such excellence, desired to know more than was lawful, in order that they might become equal with God. Here also monstrous ingratitude betrays itself.
Again, we see that the root of all obedience is and was always faith. As long as Adam and Eve were delighting in God, temptation was powerless. It was only when the turned their gaze from God’s majesty and contemplated their own abilities that sin crept it.
Their unbelief also exhibited ingratitude, as they failed to note what good they had been given. They wanted more.
And in doing so, they went crazy.