5"Woe to Assyria, the rod of my anger." Two things are true of Assyria in one breath, and Isaiah lets go of neither. She is God's instrument, sent to discipline a godless people, a rod God himself lifted. And she is guilty, worthy of the same woe pronounced on Judah's leaders, because Assyria meant to serve only herself: 7"it is in his heart to destroy." God can commission an instrument for holy work without the instrument becoming holy in the wielding.
The Assyrian king credits himself for his conquests. 13"By the strength of my hand I have done it, and by my wisdom." Every kingdom he has plundered he credits to himself, comparing Jerusalem's God to the powerless idols of cities he has already sacked, never suspecting that the campaign making him rich was never his idea.
Isaiah answers with an image almost too obvious to explain, and devastating for it. 15"Shall the axe boast over him who hews with it?" An axe is held and swung. It has never chosen what tree to fell. Crediting itself would be absurd, and Assyria has done exactly that at the scale of an empire.
16"Therefore the Lord GOD of hosts will send wasting sickness among his stout warriors." The hand that raised Assyria up now sets her down. Judgment falls on the instrument for mistaking itself for the one wielding it.
Then a single phrase carries the shift: 20"In that day the remnant of Israel and the survivors of the house of Jacob will no more lean on him who struck them, but will lean on the LORD, the Holy One of Israel, in truth." "Remnant" is the name Isaiah gave his own son back in chapter 7, Shear-jashub, spoken as a walking sermon years before this poem. That promise is cashing out, and it has been waiting through every chapter in between. The remnant leaned on the rod that struck them, and now they lean on the one who holds it.
Verse 21 names the one they return to: 21"the mighty God." It is the same Hebrew phrase used two chapters earlier for the child born to rule an everlasting kingdom (Isaiah 9:6). The remnant's return and the child's throne are one hope seen from two angles. To return to the mighty God and to bow before that child come to the same act.
22"Though your people Israel be as the sand of the sea, only a remnant of them will return." A great nation is reduced by its own long refusal to a fraction of what it was. But that fraction returns in earnest this time, leaning at last in truth on the one strong enough to hold the weight, past Assyria and past any rod an empire raises after her.
Ask what you have been leaning on that only looked strong, and whether you have been crediting yourself for something an instrument in a hand accomplished.
Prayer
Father, you have used instruments we would never have chosen, and used them rightly, even when they never intended to serve you. Forgive us the arrogance of the axe, crediting ourselves for good done through us. Keep us from leaning on the many rods this world offers, and bring us back, however small the remnant, to lean on you alone, the mighty God whose name we trust in truth. In Jesus' name, amen.