Ahaz ... did not that which was right in the sight of the LORD, like David his father. 2 Chronicles 28.1And, it's true; he did seem to lack parenting skills.
Moreover he ... burnt his children in the fire. 28.3But worst of all, he was a compulsive incense burner, burning incense in the high places, and on the hills, and under every green tree in Judah.
He burnt incense in the high places, and on the hills, and under every green tree. 28.4So, of course, God had to put a stop to that.
He did it in the usual way; he smote him by delivering him into the hand of another king (this time the king of Syria).
Wherefore the LORD his God delivered him into the hand of the king of Syria; and they smote him … And he was also delivered into the hand of the king of Israel, who smote him with a great slaughter. 28.5The text doesn't say how many of Judah's soldiers died in this smiting. But since in the next verse 120,000 soldiers die in one day, I figure it must have been at least 10,000.
God's next killing: 120,000 valiant men