What does Isaiah 20:4 mean?

God is explaining why He commanded Isaiah to walk around barefoot and uncovered for three years before Ashdod was defeated by the Assyrians (Isaiah 20:2–3). Commentators emphasize that Isaiah almost certainly wore an undergarment, such as a loincloth, during this time. The Hebrew term translated in these verses has a broader range of meaning than the English word "naked." Being seen in public, "stripped" to the humbling level of a war prisoner or criminal, on some regular basis for three years, certainly would have drawn the attention of many people.

It was a common practice in this time to strip prisoners either naked or down to the bare minimum of clothing. In a practical sense, this also made it more difficult for prisoners to run away and easier to identify. On a psychological level, the humiliation of forced nakedness drove home the point that they were truly beaten. It made them less likely to hope they could overcome the enemy that had defeated them.

Why did the Lord command Isaiah to behave so oddly? This seems to be for the same reasons God commanded some of His other prophets to engage in bizarre public displays (Jeremiah 27:1–85; Ezekiel 4:1–8). The Lord wanted to draw His people's attention to a striking visual example: how the conquered people of Egypt and Cush would look as they were marched into captivity by the king of Assyria. The people of Judah thought the Egyptians to be powerful and potential allies against the Assyrians. They could provide no refuge for Judah if they would be conquered themselves.

What did any of this have to do with the defeat of Ashdod? Some understand the Egyptians to have encouraged people, like the king of Ashdod, to rebel against Assyria. This encouragement was coupled with promises of help from Egypt. Not only did Egypt not help, but their supposed strength was also eventually stripped bare.