The fool hath said in his heart, There is no God. They are corrupt, they have done abominable works, there is none that doeth good. (Psalm 14:1)
We recognize the first day of April as April Fools’ Day. It “is an annual (primarily) Western celebration commemorated on April 1 by playing practical jokes and spreading hoaxes. The jokes and their victims are called April fools. People playing April Fool jokes often expose their prank by shouting ‘April fool(s)’ at the unfortunate victim(s). Some newspapers, magazines and other published media report fake stories, which are usually explained the next day or below the news section in smaller letters. Although popular since the 19th century, the day is not a public holiday in every country. Little is known about the origins of this tradition.”
Victims of harmless pranks can hardly be called “fools.” Anyone is susceptible to deception at the hands of someone they trust. If that is a fool, then we all qualify.
The Bible has a much harsher view of a fool. The epithet is so severe that Jesus said, “whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire” (Matthew 5:22, emphasis mine). The word “Raca” is of Chaldean origin and it means, “empty or worthless one.” A fool, on the other hand, is one who is “impious” or “godless.” Strong’s defines such a one as “dull, stupid or heedless.” The Greek word is mōros, from which we get our word “moron.” It is interesting that Jesus should offer such a severe condemnation as “hell fire” for the offense of calling someone a fool.
Jesus’ prohibition of the application of that word against another person comes at the beginning of His Sermon on the Mount. In the same sermon, He later said, “Judge not, that ye be not judged. For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again” (Matthew 7:1-2). This verse gets misquoted and misunderstood often as meaning that we are never to exercise rational discernment about someone’s actions. However, that is not at all what Jesus was saying as subsequent verses reveal. The Greek words translated as “judge” and “judgment” are krinō and krima respectively. Both have to do with making a judgment that results in condemnation and punishment. We get our English words “crime” and “criminal” from these Greek words. The kind of judgment Jesus is describing is reserved for God alone. Therefore, if judging someone as “fool” condemns the one judging to “hell fire,” then the punishment for being a “fool” must also be “hell fire.” We deduce this from Jesus’ words, “with what measure ye mete, it shall be measured to you again.” In other words, because the punishment for being a fool is “hell fire,” then the one judging the fool will receive the same judgment because only God can make that judgment.
The English word “fool” appears often in the Bible translating other Greek or Hebrew words, but the strong word Jesus used, mōros, appears only a few times and always in the context of strong condemnation. For example, in Matthew 7:26 Jesus uses it to describe the “foolish man” who built his house on a foundation of sand. Jesus likens those hear His Word and ignore it to the fool who builds his house on sand. In Matthew 25:1-13, Jesus tells the Parable of the Ten Virgins and He calls the five unprepared virgins “foolish” because they were not ready to meet the bridegroom. The condemnation is they are not allowed into the wedding. Paul warns his young protégés, Timothy and Titus to avoid “foolish” (moronic) questions because they are unprofitable and vain and they only lead to strife.
Our lead verse appears again in Psalm 53:1, “The fool hath said in his heart, There is no God. Corrupt are they, and have done abominable iniquity: there is none that doeth good.” The Hebrew word translated “fool” is nâbâl, and like mōros, it means stupid, wicked, (especially impious). Someone who does not believe in God, or rejects God is a fool. God condemns such a person to “hell fire,” which is why Jesus admonishes us not to make that judgment.
Paul describes how one sinks to that condition:
For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness; Because that which may be known of God is manifest in them; for God hath shewed it unto them. For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. Professing themselves to be wise, they became fools” (Romans 1:18-22, emphasis mine).
By examining this passage more closely, we see that “the wrath of God” – His anger, i.e., “hell fire” – is revealed “against all ungodliness and unrighteousness of men,” i.e., “foolishness.” It is doubtful that “true” atheists exist because here we see that God reveals Himself through His creation. The “invisible things,” like viruses, bacteria, atoms, quarks, etc., clearly testify to the greatness of God. Every human being on earth can see the magnificence of God’s creation so that no one has an excuse for not acknowledging God. Everyone, even the atheist, knows that God exists, but they reject Him and refuse to glorify Him choosing rather to follow their own unintelligent (i.e., foolish) imaginations. As a result, their heart is darkened. This progressive condition results in a “reprobate mind,” i.e., a mind that has lost its ability to properly reason. They think they are wise when in fact they have become fools.
“The fool hath said in his heart, There is no God” (Psalm 14:1; 53:1). And “The way of a fool is right in his own eyes” (Proverbs 12:15). “Every way of a man is right in his own eyes: but the LORD pondereth the hearts” (Proverbs 21:2). We are all fools at some time in our lives. “As it is written, There is none righteous, no, not one: There is none that understandeth, there is none that seeketh after God” (Romans 3:10-11, emphasis mine). We may all start out as fools, but we do not need to remain in that condition. If you do not know the Lord, please read my page on “Securing Eternal Life.” Don’t be an April Fool!
 Wikipedia, “April Fool’s Day” – https://en.wikipedia.org/wiki/April_Fools%27_Day
 “not pious or religious; lacking reverence for God, religious practices, etc.; irreligious; ungodly” Dictionary.Com definition – https://www.dictionary.com/browse/impious?s=t