In Matthew 5:22, we find Jesus calling one a fool. Well, from this text we see that Jesus had touched on the seriousness of wrongful attitudes and deeds that are commonly mixed into them. It should be noted here that while sin has stages, God notices the very first seed in the heart, long before it ever becomes feelings of violence and anger. Thus, failure to control oneself makes one subject to a greater punishment (James 1:13-15). Therefore, this verse is not about calling someone a fool as it is about learning to control one’s unrighteous anger.
Now, on the other side, in Matthew 23:17, we learn that Jesus said that they were “fools and blind men.” Now, Jesus earlier had called these same people hypocrites and blind guides. So, he was clearly identifying those whom he spoke against. But, when we go deeper into calling one a fool, we find Solomon stating that an atheist is called a fool (Psalm 14:1), the slanderer is said to be a fool (Proverbs 10:18), those who despise instruction are fools (Proverbs 15:5), a contentious person is a fool (Proverbs 18:6), the one who lives for pleasure is a fool (Luke 12:13-20), and the one who trusts in his won heart is a fool (Proverbs 28:26). All of these individuals are called fools by God. But, does this mean that we can call people fools?
Well, I want to point a couple of things out here. First, this word for fool in the New Testament is where we get the word for moron in the English language and that is how that word came to be. Second, this word fool simply means foolish or stupid as we find in Matthew 7:26-27 with the wise man and foolish man. So basically, those who are not built upon the rock of Christ’s teachings, are foolish.
Now, in the Old Testament, the word for fool means unbeliever, insolent in religion, stupid in practical things, foolish and idiot. These individuals are those who attack someone’s reputation, who hates instructions, who loves to disagree with others, causing controversy, who lives for their desires and lives by their own heart. So basically again, those who are not built upon God, who seek their own ways, are foolish.
Now, me personally, I would not call someone a fool because it is often a word that shuts more doors that they open. However, I have called people foolish before and would do so again should it be biblical to call them such. But sadly, there are some pretty crude people out there in the world who will call one a fool or a moron without even realizing what they are saying. I guess my point is, if they do not have a Christ like spirit in the way they present things, how would it bring glory to Christ (Colossians 3:17)?