Once again, with a long chapter it is helpful to work out how it breaks up, and what the message is in each chunk. The units seem to be vv.1-7, vv.8-13, vv.14-21, and vv.22-28. Barry Webb in his BST commentary homes in for each bit on some words of God: “Fear not!” for vv.1-7, “You are my witnesses” for vv.8-13, “I am doing a new thing!” for vv.4-21, and “I am he who blots out your transgressions” for vv.22-28. However you do it, it is worth having a handle on each chunk.
On the opening verses, Webb comments “These are some of the tenderest words here that God has ever spoken to his children”. Addressed to God’s people in exile, in the midst of the fires and deep waters of God’s judgment (cf. 42:25), it promises no quick fix but His sustaining presence. Note well what his people mean to God, and what he promises them. It’s easy to see how the language points forward to an even more costly ransom and a more far-reaching rescue.
In vv.8-13 Isaiah again creates a courtroom drama, which in part reinforces the sense that these are not fanciful ideas but facts based on hard evidence. What the nations and their idols failed to predict is the rise of Cyrus and the Persian empire, which for Isaiah still lay far in the future, but God’s people would be the living proof of the truth of his promises. They would bear witness to the truth that the LORD is God, uniquely sovereign and uniquely able to save. This salvation is described in vv.14-21 in terms of a new exodus, which will make the original exodus pale in comparison.
Verse 21 refers to the purpose of his redeeming work, but the last section then exposes how they had utterly failed to live up to it. The emphasis in v.22 is on the word “me” – “It wasn’t me you called upon, o Jacob”. There had been plenty of religious activity but no reality to it (cf. 1:10-17), it was just wearisome duty. And it wearied God. Verse 25 stands out like a shaft of brilliant light – God is the God who forgives, but can Israel make a case for why God should forgive her? The final three verses suggest not, they have no ground on which to claim pardon – it will have to be all of grace. Verse 28 could have been translated in the past tense – “So I had to …” – but if we take the NIV’s future tense then the point is that judgement is all they can expect. How God’s grace and justice will be brought together has not yet been made clear so the tension between the two is as yet unresolved.