Foolish people have foolish thoughts. The great insight into the foolish mind is the non-existence of God. They may possess a fine education and hold many degrees, but when it comes to spiritual truth they are bankrupt. "Claiming to be wise they became fools and they have exchanged the truth of God for a lie" (Romans 1). The Great Lie of the ages, "There is no God." All who have ever held to this position find their conscience warring inside against their Maker. If you want to see an unhappy person look at him. They deny the basic fundamental reason for their existence and as a result they lose their heading. They have gone out of orbit and have become asteroidal-running the gambit of the world till they burn and fizzle out. You dig them a bit about God and you'll find all sorts of angers, resentments, hostilities. They will actually become prideful in their speculations about God and his non-being. But all the while, since they are not omniscient, the phrase "what if" beats consistently in the back ground. They are terrified at the prospect and rightly so.
The fools heart speaks to him making false declarations of unholy things. Reason has been denied and rationalism and been forfeited. His reason has led him to unreasonable conclusions and his rationalism has been rationed out. This is the way in which the carnal/unregenerate mind functions. Human depravity affecting the heart. The also pat themselves on the back for "freeing" themselves from the chains of religion and traditonalism. The atheist/agnostics “coming out” is really a “going into.” He moves from one sphere to the next, a sphere that has already has been established and articulated for centuries, but as it progresses becomes more refined and defined. The attraction is actually a distraction to another matrix (mold, template, environment, atmosphere)
I've also heard that the text in Hebrew actually reads, "The fool has said in his heart-no God!" God continues to ask them questions in the heart, "Turn from your sin"-no God! "Believe on me"- no God! "Pick up and read"- no God! "I am the way, the truth, and the life"-no God! The ultimate defiance. The pot yelling at the potter, "you did not make me!" The painting telling the painter, "you did not paint me!" The watch telling the watchmaker, "you did not design me and wind me!" The apex of idiocy. They are stunted creatures, mere animals who are dwarfed in their ideas about God; retarded in growth. In everything else in life they pride themselves in being "well-rounded individuals"-in their studies, travels, music, culture, careers, relationships, but without God as the key component they lose the meaning behind it all, they lose their moral compass. Their compass spins and points to themselves, they believe they are true north; and the whole time they are on a terrestrial planet spinning through the galaxy going 67,000 miles per hour. Foolish conclusions because they have a foolish premise.
Atheism clouds the mind with a dense fog of satanic lies; it keeps man from seeing and apprehending the truth of Gods existence. Dead hearts (Eph 2) don't arrive at Living Truths. Jesus told the church at Laodecia, "I advise you to buy from me gold refined in the fire"; they think they have gold but its fools gold, they need the golden truth of Gods word. Only through rebirth (salvation) can man be brought up out of the quagmire of ignorance. Once a person is transferred from darkness to light (Col. 1), from dead in sin to alive in Christ he moves into the realm of spiritual awakedness and truth. Instead of speaking and thinking foolish thoughts he can now speak truth in his heart. Only the Spirit of God can cause this chain reaction, this metamorphosis to occur. He awakens the heart from a dead slumber and causes it to beat with the beat of Gods presence and existence. He sees with new glasses through the lens of faith with the frame of truth. The rebellion has been lifted and the pardon of forgiveness applied. Once he hated God, but now he loves God. His allegiance changes and his fist clenched at the heavens is opened. We were all fools once but love breaks through even to fools and our hard defiant disposition changes and now we are pliable, rational, logical lovers and thinkers. God has given us new hearts to think Gods rational after him, to mediate on the logic of God, to love and think with a new grid that is honoring and glorifying to Him. We no longer say no God!, but yes God! Will you go love that person that is hard to love? yes God; will you go speak my word to a people who were just like you? yes Lord. Will you fight against the injustices of the world? yes Lord. Will you take my name to the ends of the earth? yes Lord. Will you sacrificially love your wife and children without reciprocation? Yes Lord. Yes, Lord; yes Lord. It's a life characterized by this statement. The fool fights an unwinable war, a treaty has been declared 2000 years ago and through grace we now fall under this new treaty.We are all fools till we come to Christ, we are all spiritual morons till Christ is formed in us. We are now given a new teacher with a new curriculum. We have entered into a unique apprenticeship as a spiritual pupil enrolled in divine studies where the mysteries of God are unfolded and Christ is treasured. Atheism is not just an intellectual resistance in the mind but it starts in he heart. There is atheism in the heart of all men and until God quickens us we all remain in this state. We don't claim superiority to the atheist for we know its only by grace that God has drawn us out from ourselves. God has declared the atheist a fool in this text. He is a fool because of the thoughts that flow in his heart. And how you define God is what defines you.