The Bible often contrasts the foolish and the wise. In doing so, the word translated "fool" comes from different words appearing in the original text which indicate particular characteristics of individuals in the context. Most often, the word "fool" is used with regard to a moral deficiency as well as to lacking intellectual powers. In Scripture, the "fool" is primarily the person who has rejected the fear of God and conducts his life as if he can safely disregard the eternal principles of God. In other words, having rejected God, he lives accordingly.
The "fool" in our text refers to one who is rash, senseless and unreasonable. He is one who is not open to possibilities outside his own made up opinion and arrogantly insists that his opinion or belief is the only correct view (since he has rejected God's view, he opts for his own).
Therefore, when it comes to the existence of God, he insists "There is no God", hence, the idea of Divine Creation is automatically rejected and the theory of Evolution accepted on "scientific evidence", however faulty. He refuses even to consider evidence from science that supports Divine Design, because such goes against his premise that "there is no God".
Note that while the fool says, "There is no God", God replies, "They (the fools) are corrupt, they have done abominable (morally detestable) works", and that, "there is none that doeth good." In short, God declares, "You are a sinner." Cf Romans 10:10-12 and Ephesians 2:1-3.
God simply points out that the fools "reasoning" comes from his unsaved state, which is naturally estranged from God. In this sinful condition, man does not seek after God, and so rejects God's declaration of Himself in Creation (Ps 19:1-6). Because of this, God has continued to reveal Himself through HIs Word (Ps 19:7ff) and ultimately through His Son, Jesus (Heb 1:1-3).
Though mankind, in his natural state (due to the Fall in Genesis 3), rejects God and does not seek Him, God, in His great love for man (John 3:16), initiates reconciliation and seeks the lost (Luke 19:10).
The fool says by his Declaration, "There is no God", and confirms his belief by his behavior, God, like a loving shepherd seeking the lost sheep, reaches out to man. There IS a God and He HAS declared Himself, so that those who are blinded because of their sin and do not seek Him, may still be found!
Clara H. Scott wrote the hymn, "Open My Eyes, Lord That I May See". May He Who opened the eyes of those physically blind also open the eyes of those who are spiritually blind.