In this passage God turns from pronouncing judgment on the conquered nations to pronouncing judgment on their conqueror Babylon. Here, God tells them that their reign will come to a crashing end by nations from the North, that is, the Medes and the Persians.
But in the midst of this judgment, God gives a command to his people: Run!
Time and again, we see him saying things like
Flee out of Babylon; leave the land of the Babylonians (50:8),
Flee from Babylon! Run for your lives! (51:6)
Come out of her, my people! Run for your lives! Run from the fierce anger of the Lord. (51:45)
This is in sharp contrast to chapter 29 where he told the Jews to make their home in Babylon, to multiply there, and seek the peace and prosperity of the cities they were living in.
Why the contrast? Because when the Medes and Persians came, Babylon’s own time of judgment would come. And so God commanded the people to leave so that they would not get caught in Babylon’s doom.
In the same way, it would be well for us to remember not to get too comfortable as we live in this world. To keep our hearts softened to God. To remember that he is our true pasture and our hope in this world (50:7) To remember he is our creator, the one who made everything by his power and wisdom (51:15-16). And to remember that there will be a day of reckoning for all who live on this earth. (51:6, 56)
So let us leave our life of sin, and not linger in the evil that others do. Instead, let us “remember the Lord in a distant land, and think on Jerusalem.” (51:50)
Or as Paul said,
Since, then, you have been raised with Christ, set your hearts on things above, where Christ is seated at the right hand of God. Set your minds on things above, not on earthly things. For you died, and your life is now hidden with Christ in God. When Christ, who is your life appears, then you also will appear with him in glory. (Colossians 3:1-4)