Jesus moves from the act to the attitude in a single sentence. Everyone who is angry with his brother will be liable to judgment. The same courtroom that waits for the murderer waits for the person whose heart is full of unrighteous anger. This is not a softening of the law. It is the law reaching its full intended depth.
Anger that generates murder if unimpeded is the spiritual equivalent of murder. The act and the attitude share the same root: a contemptuous devaluing of another human being made in the image of God. The only difference between anger and murder, in many cases, is opportunity and restraint. God is not impressed by restraint alone. He wants a transformed heart.
It is worth noting that not all anger is sinful. God himself gets angry, and God does not sin. Jesus cleared the temple in righteous anger and grieved over hard hearts. The distinction Dale drew in Sunday’s sermon is helpful here: righteous anger reacts to actual sin, focuses on God’s kingdom rather than personal offense, and expresses itself in godly, controlled ways. By that measure, most of what we call righteous anger is actually something else entirely.
Most of the anger we carry is anger over petty offenses to our own honor. We burn hot when we are disrespected, overlooked, or wronged. We are slow to anger when God is dishonored, and quick when our pride is bruised. This is the anger Jesus is confronting: the cold, self-focused contempt that says, deep down, that another person does not deserve the dignity God has given them.