The plan of this study is simple. We will look at a large number of sins, one by one, alphabetically. We will define the sin, describe it, and comment on it, along with noticing Scripture references on the particular entry. Some illustrations will be offered along with the description.
I well recall the incident as a child. My brother, six years my junior, must have done something I considered unwise. Although the circumstances are lost from my memory, I can still hear my mother warn me: Richard, the Bible says that we must not call someone a fool! I had never thought of this and probably didnt know what Scripture she had in mind, but her words did burn into my heart and I dont think Ive used the term in this way again. We are not implying that it is ever wrong to use the term fool or foolish in our conversation, but we must not use it in the way Jesus condemned in the Sermon on the Mount.
People sometimes use the terms fool and foolish in their everyday language. In our language, fool can mean a silly or stupid person, and foolish can mean, resulting from or showing a lack of sense. . . . lacking forethought or caution.
Lets notice what else the Bible adds to this. Scriptural terms for fool and foolish do have some of these thoughtsand more. In the Old Testament, several different terms are used for fool, foolish, and folly. Fool can denote fool, a stupid or shameless person, one who hates knowledge (Proverbs 1:22) and takes no pleasure in understanding (18:2). He displays a defective moral character.
Foolishness is a moral rather than a mental issue. The fool is morally deficient. It includes insolence and rebelliousness. Another Hebrew term refers to an obstinate person, who persists in making choices that lead to destruction.
Solomon tells us: The fear of the LORD is the beginning of knowledge; fools despise wisdom and instruction (1:7). Fools also display dishonor (3:35). Further, the mouth of fools feeds on folly (15:14). A fool will speak foolishly. David says, The fool has said in his heart, There is no God. They are corrupt, they have committed abominable deeds (Psalm 14:1; cf. 53:1).
The quick-tempered person exalts folly (Proverbs 14:29). Scripture says that foolishness is bound up on the heart of a child; the rod of discipline will remove it far from him (22:15). Is this the kind of child you want your son or daughter to associate with?
The New Testament uses different terms to refer to fool and foolishness. The word aphron means foolish, senseless and can mean fool. The root term phron indicates wisdom, reason, or insight, the prefix a indicates a lack of wisdom, reason, or insight. . . . Aphron does not indicate a lack of knowledge but an inability to use it correctly. Paul says, Do not be foolish, but understand what the will of the Lord is (Ephesians 5:17).
The fool is little concerned about either God or His will. Jesus said of those Pharisees who were concerned about the externals but cared little about the internal, You foolish ones, did not He who made the outside make the inside also? (Luke 11:40). The Lord gave a parable about a wealthy farmer who was only concerned about piling up riches, saying to his soul, Soul, you have many goods laid up for many years to come; take your ease, eat, drink and be merry (Luke 12:19).
What was Gods perspective? He said to the man, You fool! This very night your soul is required of you; and now who will own what you have prepared? (v. 20). A fool, a foolish person, is only concerned about the presentand not about his eternal destiny!
Another term is moros, which means fool as a noun or foolish when used as an adjective. In the NT moros is often contrasted with wisdom (phronimos). Foolishness often denotes not only simple stupidity, but ignorance of and willful rebellion against God and his will.
At the conclusion of His Sermon on the Mount, Jesus tells the parable of the two foundations. The wise man was like the man who built his house on a rock. When the rain fell and the floods came, the house stood because he had built the house on a rock. This is likened to a man who builds the house of his life on the solid foundation of Christs teachings (as found in the Sermon on the Mount).
On the other hand, there was a foolish man who built his house on the sand. When the rain fell and the floods came, the house fell. It was not able to withstand the storm because of the faulty foundation. This is the person who disregards Christs teachings. He represents everyone who hears these words of Mine and does not act on them (Matthew 7:24-27). The fool fails to listen to or read Gods Words and lives his life as though they didnt even exist.
The Lord also uses moros to refer to five of the ten virgins who were waiting for the wedding feast (Matthew 25:1-13). Five of the virgins were foolish since they didnt bring enough oil for their lamps and when they were gone to buy more oil, the wedding feast began and the door was shut, leaving the virgins outside. They had no spiritual discernment. They lacked spiritual forethought. Jesus also uses moros to refer to the scribes and Pharisees who were concerned about the minutia of the law but neglected the weightier provisions of the law; justice and mercy and faithfulness (Matthew 23:23). The Lord calls them, You fools and blind men! (v.17).
Paul also uses the terms, fool and foolish and foolishness. He wrote, The wisdom of this world is foolishness before God (1 Corinthians 3:19). Any philosophy or ideology that leaves God out of life is in reality foolishness. This would include the many humanistic views prevalent and even dominant in our day! There are PhDs who are fools in the sight of Godand they should be in our view as well.
A further word is anoetos, meaning not understanding, from a, a negative, and noeo, to perceive, understanding. Paul writes, You foolish Galatians, who has bewitched you, before whose eyes Jesus Christ was publicly portrayed as crucified? (Galatians 3:1, cf. v. 3). They had deserted Christ and the significance of His death for them and were returning to justification by the Law. Paul also says, We also once were foolish ourselves, and characterized this foolishness as involved with disobedience, deception, and being enslaved to various lusts and pleasures (Titus 3:3). The apostle also speaks of those who want to get rich who fall into temptation and a snare and many foolish and harmful desires which plunge men into ruin and destruction (1 Timothy 6:9). This is the consequence of unbridled greed and materialismfoolish and harmful desires.
Foolishness definitely is a sin of our age since people generally dont value the knowledge of God and have little or no interest in following the will of God. They even deny the existence of God. They are more concerned about material pursuits than seeking the Lord and His service. In Biblical terminology, they have become fools and live a foolish life! When they deny God and follow their humanistic conception of gods, God says, Professing to be wise, they became fools! (Romans 1:22).
 Random House Websters College Dictionary.
 Mounce, Expository Dictionary.
 Richards, Expository Dictionary.
 Mounce, Expository Dictionary.
 W. E. Vine, Expository Dictionary.