When the Lord has finished all his work on Mount Zion and on Jerusalem, he will punish the arrogant boasting of the king of Assyria and his haughty pride. For he says:
“By the strength of my hand I have done it,
and by my wisdom, for I have understanding;
I have removed the boundaries of peoples,
and have plundered their treasures;
like a bull I have brought down those who sat on thrones.
My hand has found, like a nest,
the wealth of the peoples;
and as one gathers eggs that have been forsaken,
so I have gathered all the earth;
and there was none that moved a wing,
or opened its mouth, or chirped.”
Shall the ax vaunt itself over the one who wields it,
or the saw magnify itself against the one who handles it?
As if a rod should raise the one who lifts it up,
or as if a staff should lift the one who is not wood! (Isaiah 10:12-15)
Whatever good you manage to accomplish, it is actually God who did it (see 1 Corinthians 15:10, Philippians 2:13). In 722 BC the Assyrians would conquer the Northern Kingdom of Israel and carry a bit less than 30,000 people away as captives. God decided to bring the Assyrians against the Israelites to punish them and by so punishing, to help them realize the error of their ways so that they could repent and turn back to God.
Unlike God, the Assyrians cared only about conquest. They imagined themselves to be in charge of their own fates, achieving their own ends, oblivious to the hand of God in their lives.
Although God judged his people, they remained his people—and there remained the old promise he had made to Abraham: “those who curse you, I will curse.” (Genesis 12:1-3) So even though the Assyrians were fulfilling God’s purposes, they fell under his condemnation, both for their arrogance, and for daring to harm Israel.
God’s judgment on Assyria fell within two generations, when the Assyrian army, together with their Egyptians allies, were defeated at a place called Carchemish in 605 BC by Nebuchadnezzar and his father. God judged the judgmental.