Here’s the big idea in this connection for me.
Isaiah 40—55 works in linear fashion and it simply declares that God’s purpose is about to be fulfilled. Isaiah 56—66 works chiastically: it goes round in circles. It is set the other side of the events that Isaiah 40—55 heralded and it knows that they had not brought the consummation of God’s purpose.
Isaiah 56—66 is prophecy for a time when nothing is happening, when all a prophet can do is reaffirm God’s promises and reaffirm God’s expectations and model the kind of prayer one prays in such a situation and equip the people of God for the long haul.
The importance of its message has come home to me in our own context. Isaiah 1—39 promised the coming of a reign of peace and justice, and Isaiah 40—55 promised the consummation of God’s purpose, and the New Testament declares that in Jesus God has fulfilled those promises.
Seven hundred years passed from the time of Isaiah ben Amoz to the coming of Jesus. Three times as many years have passed since the coming of Jesus, and (as 2 Peter 3:4 puts it) things continue as they were from the beginning of creation. While a countless host all over the world has come into a relationship with God since Jesus’ coming, and they will be the citizens of the heavenly Jerusalem, here in this world Jesus’ coming has made little difference. As Jesus put it, wars and rumors of wars continue. Slavery on a vast scale continues. Poverty on a vast scale continues.
Isaiah 56—66 was designed for a time like our time. It reminds us to hold onto God’s promises, to re-commit ourselves to God’s expectations, and not to give up on prayer like that of the woman in Jesus’ parable who is making trouble with the unjust judge.