With Isaiah 21, we return again to the nation of Babylon, making a neat loop of the nations surrounding Judah. But why, if Babylon was not a threat, does she get a double mention?
Remember: Isaiah the writer began his prophetic ministry about 740 B.C. He ministered to the southern nation of Judah. During his ministry, the northern nation known as “Israel” would be overcome by the Assyrians. Isaiah spoke to the people of his day about current events and about their spiritual failings. What Isaiah said to them is written in this book. But what he wrote was for someone else: the generation of Judah that would live 150 years later – the generation that had seen the southern kingdom fall to the Babylonians. Babylon was nothing to Judah in the days of Isaiah. But she was very much something to those who would read the book during the Babylonian captivity. By hitting Babylon, Edom and Arabia twice, the readers would know that their greatest enemies would be destroyed by the Lord – just as her former enemies had met their demise in the past – all according to the word of Isaiah.
When chapter 21 opens and the prophet finally turns his attention to Judah (Jerusalem), the readers can know that his word concerning them is true too.