As the king goes, so go the people
When the righteous are in authority, the people rejoice: but when the wicked beareth rule, the people mourn. -- Proverbs 29:2
I wonder to what extent King Hezekiah's righteous reformation of Judah was motivated by grief over his siblings being burned to death by his evil father King Ahaz in sacrifice to demons. While Scripture doesn't explicitly state it, it is safe to assume that Hezekiah was aware of what was going on. God often uses children to rebuke their parents' sins, something I have seen in my own life when my four-year-old has called me out from time to time.
Perhaps the saddest part of Hezekiah's life story, though, was the rebellion of his evil son Manasseh. Hezekiah purged Israel of demon worship, and brought the people's hearts back to the only true God. This was a wonderful thing. But Hezekiah's own son would plunge Judah back into demon worship, burning his own children (and Hezekiah's grandchildren) to death in sacrifice to demons. This cut me deeply. Those of us who advocate for righteousness in public life must not fail to discipline and instruct our own children. In fact, there is a reason that the Apostle Paul instructs believers that church elders must run their own homes well.
It was not until King Josiah (Manasseh's grandson) that Judah repented again of demon worship. But by then it was too late. God's judgment was already on Judah, because they had filled up His cup of wrath. God in His kindness promised the judgment would not fall as long as Josiah was alive, but the judgment would come. Thankfully, this was all part of God's plan to eventually bring salvation to all peoples.