The psalm begins with an assessment of a fool who does not believe in the existence of God. Some scholars think that David is speaking about the incident involving Nabal (his name means ‘fool’) in 1 Samuel 25 and uses his character as a description of all who oppose the work of God’s kingdom.
In the Old Testament, the terms ‘fool’ and ‘folly’ don’t refer to a person’s lack of intelligence. Instead they describe the opposite type of person to the ‘wise’ man and his way of life (‘wisdom’). The fear of the Lord is the beginning of wisdom and such reverential fear marks the wise person in the Old Testament. The fool, in contrast, concludes that he has no need to fear God and lives as if he did not exist (v. 1). Why do the 'fools' make this conclusion? The answer is that their hearts are full of sinful intentions (v. 2). Their choice is not based on evidence, but on desire. The fools want to sin.
Nevertheless David is aware of one great reality, which is that God is continually assessing the minds and intentions of humans, including the fools (v. 2). What does God find? He discovers that corporately they have departed from his ways and become increasingly dishonest, and not even one of them is determined to do good – in the sense of obeying God’s commandments (v. 3). Further, they persecute God’s people and never pray to him (v. 4). David therefore realises those who deny the existence of God have no basis for discovering true personal knowledge of reality, and have no restraint preventing them from personal and increasing sin.
Eventually there comes a situation in which the atheist’s views are tested. David says that then the fool, who previously scoffed at the existence of God, will sense his angry presence and be in great terror in a situation that causes no fear to those who trust in the Lord This was the case with Nabal who became afraid of David when there was no longer a need for such a response (1 Sam. 25:32-37). What happened to Nabal is a picture of what happens to those who oppose God’s kingdom – eventually God deals with them and, instead of triumphing over God’s people, they will be put to shame (v. 5).
Thoughts about the foolish in Israel causes David to long for the spiritual restoration of God’s people. He wants the Lord who dwells in Zion to deliver his people and restore their former prosperity. When that happens, God’s people will be full of joy (v. 6).
This psalm is a reminder that we are not to be overawed by the claims of God’s enemies. Instead we are to imitate David and mention their foolishness to God. We are also to praise God for the fact that he will yet come and deal with his opponents and give spiritual recovery to his people. There are plenty atheists about today, who imagine they know a lot. But they don’t know what we know, which is that God is assessing them and will eventually deal with them and restore his cause.