There are two main reasons why this passage is problematic: it seems to forbid something which is done elsewhere in Scripture, and it offers a very strong penalty for something which does not seem that bad. It has to do with using the term “fool” against other people. The last part of this passage says, “And anyone who says, ‘You fool!’ will be in danger of the fire of hell.”
A lost eternity simply for calling somebody something unpleasant? And didn’t others in the Bible use the very same term? On both questions we can offer some explanation to resolve these apparent difficulties. The first and main consideration to raise here is that which helps in many such cases: consider carefully the context.
And the context is this: Jesus wanted his listeners to know that our outward sins are basically reflections of inward evil. The Sermon on the Mount highlights this truth quite forcefully, to counter the Pharisees and others who think they are right with God if they simply refrain from doing certain outward actions, while ignoring their inward inclinations and attitudes.
The first two verses of this section say this:
“You have heard that it was said to the people long ago, ‘You shall not murder, and anyone who murders will be subject to judgment.’ But I tell you that anyone who is angry with a brother or sister will be subject to judgment. Again, anyone who says to a brother or sister, ‘Raca,’ is answerable to the court. And anyone who says, ‘You fool!’ will be in danger of the fire of hell.”
Jesus is saying that murder originates in the heart. Those who resort to murder have already hated others in their heart. And since Jesus here insists on perfection before a perfect God (“Be perfect, therefore, as your heavenly Father is perfect” – Matt. 5:48), he has to highlight what is in the human heart.
It is from within that sin is birthed. Even if you have never murdered a person, Jesus makes it clear that if you hate someone, it is the same as murdering that person. This key point is driven home even further in verses 27-28: “You have heard that it was said, ‘You shall not commit adultery.’ But I tell you that anyone who looks at a woman lustfully has already committed adultery with her in his heart.”
Here we have the very same principle at work. If you pride yourself in never having committed adultery, think again. If you have ever lusted after someone, it is the same as committing adultery. Inner attitudes are just as important to God as are outward actions.
So in this sense, to hate someone enough to call him a fool is not unlike murdering him. In that sense, yes this is a very serious matter indeed. So this in good measure helps to explain why it seems that the punishment is disproportionate to the crime. Our inner state matters as much to God as do our outward actions.
But what about the other concern? Do not others use the very same word in Scripture? Yes they do. God uses the word, as does Jesus, and Paul, and others. The book of Proverbs for example is full of talk about the fool. Here and in the rest of the Wisdom literature the fool connotes someone who is “thoughtless, careless, conceited, self-sufficient, indifferent to God and His Will, or who might even oppose and scoff at religion and wise instruction”.
A good summary of what a fool is like is found in Isaiah 32:6:
For fools speak folly,
their hearts are bent on evil:
They practice ungodliness
and spread error concerning the LORD;
the hungry they leave empty
and from the thirsty they withhold water.
Of the dozens of references to fools in Proverbs, here are just two: “A fool finds pleasure in wicked schemes, but a person of understanding delights in wisdom” (Prov. 10:23); “Eloquent lips are unsuited to a godless fool— how much worse lying lips to a ruler!” (Prov. 17:7).
And God refers to the atheist as a fool, as in Psalm 14:1 and 53:1, which both basically read: “The fool says in his heart, ‘There is no God.’ They are corrupt, their deeds are vile; there is no one who does good.” Or the Psalmist could say, “Rise up, O God, and defend your cause; remember how fools mock you all day long” (Psalm 74:22).
Jesus also spoke about those who were fools, or those who at least did foolish things. For example, in Matt. 23:17 he said “You blind fools!” And in Luke 11:40 we read: “You foolish people! Did not the one who made the outside make the inside also?”
Paul could say in Romans 1:21-23: “For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened. Although they claimed to be wise, they became fools and exchanged the glory of the immortal God for images made to look like mortal man and birds and animals and reptiles.” And he chewed out the Galatians as well in this fashion: “You foolish Galatians! Who has bewitched you?” (Gal. 3:1).
So were all these people wrong to use such language? It seems the way to resolve this tension is to admit that not all words are spoken in anger, and/or not all anger is sinful. In fact we speak of such things as “righteous indignation”. Jesus surely had this, as when he rebuked those in the temple (John 2:13-17).
The same with Paul. He often showed some righteous indignation when those whom he loved got the gospel wrong, or fell into sin. And there is a sense in which we too should have some righteous indignation. I discuss this elsewhere, eg: https://billmuehlenberg.com/2007/06/16/righteous-indignation/
And Ephesians 4:26 makes it clear that not all anger is sinful: “In your anger do not sin: Do not let the sun go down while you are still angry.” So there can be anger which is not of the sort that Jesus was condemning back in Matt. 5:22. Indeed, some Bibles will have this phrase added: “without cause”. That is, the verse will say, ” But I tell you that anyone who is angry with a brother without cause…”
If so, most good Bibles will have a marginal note at this point showing that our earlier and best manuscripts do not contain this phrase, but it was added later to the Greek text for clarification purposes. So even though it is not in the original, those who added it were making a valid theological point. There is such a thing as anger with a cause, as well as anger without a cause.
This discussion may not have resolved all of our questions here, but hopefully it may have helped to some extent. It seems that looking at the context assists us in clarifying things, as does appealing to the biblical truth that some anger may at times be justified.