Man's condition by nature is Godless. He acts as though there were no God, he thinks and plans as if there were no God. In both his heart and his life he says, by implication: "there is no God" (Psalm 14:1). God is not in all his thoughts. This is the heart of man by nature, "there is none that understandeth, there is none that seeketh after God" (Romans 3:11). Because God is not in all his thoughts "every imagination of the thoughts of his heart [is] only evil continually" (Genesis 6:5).
Man sins and yet does not fear the retribution of God, he despises the forbearance of God's mercy and shrugs his shoulders, so to speak: "he hath said in his heart, Thou wilt not require it" (Psalm 10:13).
It is not just that men forget God "days without number" (Jeremiah 2:32), fundamentally they do "not like to retain God in their knowledge" (Romans 1:28).We all know God but at the same time we do not know Him. He is the God who is "not far from every one of us" but He is also "the Unknown God" (Acts 17:27 & 23). Can it surprise us to read that the "thoughts of the wicked are an abomination to the LORD" (Proverbs 15:26)? The Bible also states in Psalm 10:4 that: "The wicked, through the pride of his countenance will not seek after God: God is not in all his thoughts."
Perhaps you thought that only the very worst of the worst could be called "wicked": murderers, adulterers, extortioners and the like. The Bible, however, makes it clear that the wicked are God-rejecters and God-neglecters, they will not seek after God, He is not in all their thoughts. It is not a question of degree, that they are the worst, it is a question of nature. Do you have a heart that excludes God?
Godless Thinking in Daily Life
Intellectually speaking, those thoughts may be lofty, logical and admirable yet morally speaking because there is a proud, self-sufficiency underlying them they are tainted by the wickedness of a Godless heart. The Scriptures teach man that his highest reason for being on this earth and the deepest meaning of life itself is to glorify God in whatever we do, even in eating and drinking (1 Corinthians 10:31). Yet man refuses to serve God. Thus, we read that even "the plowing of the wicked is sin" (Proverbs 21:4), because it is done without reference to the God on whom he is dependent for the skill and success of such work. The plans and thoughts of man's heart are unceasing, and yet they have no provision for the sovereign will of God. Men ought to say, if they understood aright, "if the Lord will, we shall live, and do this or that" (James 4:15). They ought to commit their plans to the Lord, who alone can establish them, but God is not in all their thoughts.
Godless Thinking in Religion
It seems absurd that man can pursue his Godless thinking into religion but only a little reflection confirms that this is so. Man takes his own way, according to his own thoughts, indeed false religion is always focussed on the works of man as the ground of salvation rather than the work of Christ. "There is a way that seemeth right unto a man but the end thereof are the ways of death" (Proverbs 14:12). Man will seek out his own inventions for his own glory, whether it be the blaspheming rationalistic theologian tearing at the Bible or the diligent churchgoer going about to establish his own righteousness. There are some on the other hand who will claim to be religious but they still believe that they can live their own life of disobedience (Deuteronomy 8:11, 29:19). Man will tailor things to himself; adding to what God has revealed and taking away from it at his own pleasure.
What man can pervert he will pervert. Even when he attends orthodox worship, man thinks he is doing God a favour and that there is merit in attendance. But he will not give the heart, his lips may express praise but his thoughts and heart are far from God (Proverbs 15:8, Mark 7:6). Men will also reason to themselves "I'm not as bad as others, God will accept me as I am", forgetting the holiness and justice of God. The reply that comes from God himself, however, is: "thou thoughtest that I was altogether such an one as thyself: but I will reprove thee, and set them in order before thine eyes" (Psalm 50:21). God is not in all the thoughts of the wicked.
The Remedy for Godless thinking
The gospel call comes to the sinner in terms of a command to repent (literally, a change of mind), and a command to abandon his Godless thoughts. "Let the wicked forsake his way, and the unrighteous man his thoughts: and let him return unto the LORD, and he will have mercy upon him; and to our God, for he will abundantly pardon" (Isaiah 55:7). Like the prodigal son, the sinner in conversion to God, comes "to himself" (Luke 15:17). There is a radical change, the thoughts are now taken up with God (Isaiah 26:8, Psalm 73:25). The believer "hates vain thoughts" but loves the Word of God (Psalm 119:113) which teaches him how to think aright. His mind becomes renewed and sanctified according to the truth. He will ask God to single out his offensive thoughts that they may be repented of (Psalm 139:23). Instead of an arrogant self-sufficiency and self-absorption he has the mind of Christ, an attitude of humility towards others (Philippians 2:5). Instead of God not being in all his thoughts, he seeks to glorify God in his body and in his spirit, which are God's by redemption through the perfect, finished work of the life-giving sacrifice of Christ.
Is this you?
If not, then "how long shall thy vain thoughts lodge within thee?" (Jeremiah 4:14).