There is the old Jerusalem with its temple - the House of God. It represents the pinnacle of human and religious strength. If anywhere could be safe from the coming judgement, it would be Jerusalem. Yet the LORD repeatedly asserts that Jerusalem is first in line for divine judgement.
A few examples:
In Isaiah 5 there might be a 6-fold "woe" pronounced on the people in general, but it culminates in the temple with the LORD's own prophet (Isaiah 6:5).
When the LORD commissions Isaiah to preach to Jerusalem, his preaching will completely cut down the tree until only the Holy Seed is left. (Isaiah 6:13)
When Isaiah pronounces oracles against the nations (Isaiah 13-21) they culminate with Jerusalem (Isaiah 22; 29-31).
In Isaiah 51, it is Jerusalem that will drink the cup of the LORD's wrath first (cf Jeremiah 25).
Yet on the other side of this judgement comes a salvation that is also "to the Jew first."
Isaiah is cleansed by fire from the altar (Isaiah 6:7)
The holy Seed will come as a shoot from the stump of Jesse to be universal Ruler (Isaiah 11).
After cosmic judgement, our hope will be manifest "On this mountain" (Isaiah 25:6) but "On that day" (Isaiah 25:9).
After drinking the cup, the LORD takes it out of Zion's hand and comforts them (Isaiah 40:1ff; 51:22)
So we see that judgement and salvation as preached by Isaiah is not like this:
It's not that good behaviour could ever avert the judgement of God that rests on Jerusalem. Instead it's like this:
Or, to be more precise, it's like this:
Judgement begins with the house of God (1 Peter 4:17). Israel is the house(hold) of God. The temple is the house of God. And, in fact, the world is the house of God. But it's all scheduled for demolition - from the top down.
Yet what about this holy Seed? What about this Offspring of Jesse? Surely He will sum up Israel - isn't that what a King does? Represent people?
What about this Servant King who is the covenant (Isaiah 42:1-6)? What about this Anointed One who takes up the lost cause of His people? (Isaiah 61). He will bring salvation to Zion, light to the nations, peace to the ends of the earth (Isaiah 11). First He must suffer in a very temple-kind-of-way (Isaiah 53:1-10) and then be glorified (Isaiah 53:11-12). In this way He will sprinkle clean many nations (Isaiah 52:15). They will stream to the true House of God (Isaiah 2:1-4) and so salvation can reach the ends of the earth (Isaiah 65-66).
In this way the preaching of Isaiah is classically law-gospel. There is the righteous judgement of God which cannot be evaded by any of our own righteousness (Isaiah 64:6). And there is one hope for us - the Divine, Davidic Christ of God. He alone bears our punishment and rises to give life. We who receive His word are brought into His eternal covenant and blessed with all His divine blessings (Isaiah 55:3).
Luther did not invent such a paradigm. It pulses through the Scriptures. Because all the bible preaches salvation by grace alone, through faith alone, in Christ alone.