Why did Paul and Jesus call people foolish when Jesus taught us not to call our brother a fool?

from the old testament

• Genesis 1:27 expresses the key reason that all human beings are intrinsically valuable: “So God created man in his own image, in the image of God he created him; male and female he created them.” Our behavior towards others should show our awareness that they are created in God’s image. That includes avoiding insults, like raca (see Matthew 5:22), that diminish someone’s intrinsic value as an image-bearer of God.
• Genesis 9:6 communicates that we have value because we are made in God’s image: “Whoever sheds the blood of man, by man shall his blood be shed, for God made man in his own image.” God sets the severest punishment for taking a human life because we are image-bearers. Similarly, Jesus condemns vulgarly insulting someone because to do so shows a disregard for those who are made in God’s image.
• In Psalm 8:4, David rhetorically asks God, “What is man that you are mindful of him, and the son of man that you care for him?” This may make it seem as if David is diminishing the importance of the pinnacle of God’s creation (mankind). But the Psalm continues by outlining all the honor that God has given us: “Yet you have made him a little lower than the heavenly beings and crowned him with glory and honor. You have given him dominion over the works of your hands; you have put all things under his feet” (Psalm 8:5–6). These blessings show our worth in God’s eyes, which we should always keep in mind when interacting with others.

from the new testament

• In Matthew 5:22, Jesus warned people about the way they talked to others. Jesus said, “whoever says, 'You fool!' will be liable to the hell of fire." The Greek root for the word translated fool there is raca. It means empty, senseless, empty-headed. Raca is a term of reproach, expressing a judgment call on someone's humanity. Using that term about a brother would be wrong for those who claim to follow Christ.
• Jesus said believers are to be salt and light (Matthew 5:13, 14), to let our “light shine before others” so that they will see our example “and give glory” to God (Matthew 5:16). Our words matter.
• In Galatians 3:1 Paul calls people foolish, using the term anoetos. This refers to not understanding or being unwise. This isn’t a character judgment about one’s worth. Paul was not angrily insulting others, he was pointing out the error in the Galatians’ belief.
• In 1 Corinthians 1:25–27, 1 Corinthians 3:18, and 1 Corinthians 4:10 Paul speaks of being a “fool” in the eyes of the world using the word moros. He is making points about how the world views the gospel, the dangers of self-deception, and the Corinthians’ view of the apostles that stemmed from false teachers. These are not personal insults, but rhetorical maneuvers to distinguish the truth of the gospel from the wisdom of the world.
• In Matthew 22:37–39, when Jesus was asked about the greatest commandment, He replied, “You shall love the Lord your God with all your heart and with all your soul and with all your mind. This is the great and first commandment. And a second is like it: You shall love your neighbor as yourself.” Using angry insults like “fool” is the opposite of those two commandments. Loving God entails that we love those who bear His image and that we act accordingly.
• Words often reflect the heart. This is highlighted in Matthew 12:34 when Jesus notes that “out of the abundance of the heart the mouth speaks.” He warns that “on the day of judgment people will give account for every careless word they speak” (Matthew 12:36). This connects to Jesus’ admonishment against calling someone raca. It also points to the need for a Savior since we all speak carelessly at times.
• The mouth as a conduit of the heart is all the more disturbing as it reveals the evil that could be in our heart toward others. Colossians 3:8 cautions believers to “put them all away: anger, wrath, malice, slander, and obscene talk from your mouth.” Raca is “obscene talk.” This verse also reveals that our hearts can harbor sin and that we would be condemned if not for Christ.
• The challenge of controlling our speech is explored in James 3:8–9: “but no human being can tame the tongue. It is a restless evil, full of deadly poison. With it we bless our Lord and Father, and with it we curse people who are made in the likeness of God.” The latter part of the verse implies chastisement for cursing others since they “are made in the likeness of God.” This fits with Jesus’ message in Matthew 5:22. And though “no human being can tame the tongue,” with the Holy Spirit, we gain the strength to do so.

implications for today

Think about the last time you were angry. How did you react? Every day, we encounter others who annoy us. Maybe it’s the person who cut you off in traffic. Or maybe it’s a relative who cut you out of your rightful inheritance. Even as believers, we sometimes react to such circumstances with anger, maybe even insulting the target of our ire. Because of our love for God, though, we are called to speak to others with the awareness that they are God’s image-bearers (cf. Ephesians 4:15, 29; Colossians 4:5–6). Jesus connects calling someone raca to the sin of anger and indicates that it is grounds for judgment (Matthew 5:22). Followers of Christ should always try to avoid behavior that does not glorify our Heavenly Father. But in our current state, we’re still bound to sin. Matthew 5:22 and other portions of Jesus’ Sermon on the Mount point to our sinful heart and our need for Christ. Without Him, we really would be condemned for angrily calling a brother “fool” (John 3:16–18, 36; Romans 5:6–11; Ephesians 2:1–10). All of us have value by virtue of being made in God's image (Genesis 1:26). We can disagree with others. We can warn them if we notice them erring. But we should avoid speaking to others in any way that diminishes their intrinsic value as fellow image-bearers. Our communication with others should be “seasoned with salt” (Colossians 4:6) rather than with insults.