The title is important. The reality of satan’s existence is a powerful fact in the Garden. The fact of satan’s reality in the garden seems ample enough argument for believing his lie. Think of it in terms of this, here is one who is openly defying the Lord God and yet is still alive. This is a powerful reality. And this fact brings to question the validity of God’s statement. Several things begin to be in question, “how can God allow such a being to continue in existence?" With energy, cunning and vitality he challenges the very rule and the very interpretation of that law which demands death for disobedience and yet this serpent lives. How can this be?
Perhaps if such defiance does not result in death then neither would defiance against eating of this fruit. Again, the argument is compelling and strengthening.
Only if God is not believed to be as He has so far appeared to be, i.e. the Sovereign God of all creation and from whom obedience is demanded, can this be so. Existence, which derives from God, becomes part of the argument against God. Satan is alive and well. He is real and he exists. The facts seem to mitigate against God’s sovereign rule in the universe. Things do not appear to be as obedient to Him as He claims they ought to be. The dragon asks, “Who is He to make such demands?” (which questions God’s character) He has not stopped this being from open defiance. (which questions God’s power). This being gives me choice in the matter. (which questions the sovereign rule and legitimacy of obedience to God).
That which is seen becomes more convincing than what is unseen. Where is the omni-present God? It is not merely the silence of Adam which is compelling but most certainly the silence of God. The lusts of the eyes (the fruit is appealing and the existence of very real opposition to God) the pride of life (i exist and no one stops me in my choice, I decide whether God is a liar and a lie) and the lust of the flesh (what I can see, feel, taste, touch; that which is sensate is ultimate reality and the definer of what is true).
We repeat these things daily.