The Lord's judgment would make the Moabites embarrassed that Chemosh could not protect them. This is similar to how the Israelites of the northern kingdom felt when the false gods they worshiped could not protect them from the Assyrians (1 Kings 12:28–29; 13:33–34; Hosea 8:5–6).
ashamed when they trusted in Bethel: See 1 Kings 12:28–30.