What does Matthew 27:37 mean?

The charge against the prisoner being crucified was often put on a sign above his head. This ensured that the populace would see the price of such crimes. Crucifixion's entire design was centered around terror, humiliation, pain, and dominance. Merely ending life was not the point; its greatest benefit to Rome was as a deterrent. Hanging mutilated corpses where they could be seen sent a clear message about what happened to those who defied the Empire.

Pilate, as the Roman governor, may or may not have personally written down these charges. Whether that was the case with Jesus, or if Pilate "wrote" this by dictation is irrelevant. Pilate faced an unexpectedly difficult choice of what to write. He openly declared Jesus was innocent of the crimes for which He was accused (Luke 23:4, 14). Once he gave in to mob pressure, however, the governor shifted to focus on the idea of Jesus as a self-appointed King (John 19:14–15).

Matthew's reference to Jesus' crucifixion label was "Jesus, King of the Jews." John further clarifies that Jesus' identity was specified as "Jesus of Nazareth, King of the Jews" (John 19:19). Written in three languages, it was meant to be clearly seen and understood. Ironically, this was exactly the truth, published for all who saw it. At the urging of the Jewish religious leaders, Rome had crucified the Christ, the Messiah, the rightful king of Israel.

The phrase "Jesus of Nazareth, King of the Jews" translates into Latin as Iēsus Nazarēnus Rēx Iūdaeōrum, initialized as I.N.R.I. This shorthand version is often seen in artistic representations of the crucifixion.

Stating that Jesus was Israel's King irritated Jewish religious leaders even further. Pilate might even have chosen this wording out of spite. Those who saw the sign, without knowing all that had happened before, would assume Rome was crucifying Israel's actual, recognized king. The chief priests hated that and asked Pilate to change it to clarify that Jesus claimed that role. Pilate's reply was, "What I have written I have written." (John 19:21–22.)