2 Chronicles 34-36: The People Have Spoken

Time is running out for Judah and it is not just the fault of their leaders, though with the exception of Josiah, none of the kings after Hezekiah paid attention to God or his laws.  But you can't blame the decline of Judah on the kings.  Instead, the kings just mirrored the people.  They gave the people what they wanted.

The LORD, the God of their fathers, sent word to them through his messengers again and again, because he had pity on his people and on his dwelling place.  But they mocked God's messengers, despised his words and scoffed at his prophets until the wrath of the LORD was aroused against his people and there was no remedy. - 2 Chron 36:15-16 NIV

One of those messengers was Jeremiah who was alive during the reign of Josiah.  God showed Jeremiah that the sins of Judah had become even more egregious than those of Israel, who had already been taken into captivity.

During the reign of King Josiah, the LORD said to me, "Have you seen what faithless Israel has done? She has gone up on every high hill and under every spreading tree and has committed adultery there.  I thought that after she had done all this she would return to me but she did not, and her unfaithful sister Judah saw it.  I gave faithless Israel her certificate of divorce and sent her away because of all her adulteries. Yet I saw that her unfaithful sister Judah had no fear; she also went out and committed adultery.  Because Israel's immorality mattered so little to her, she defiled the land and committed adultery with stone and wood.  In spite of all this, her unfaithful sister Judah did not return to me with all her heart, but only in pretense," declares the LORD.

The LORD said to me, "Faithless Israel is more righteous than unfaithful Judah." - Jeremiah 3:6-10

In the end, God is not looking for a godly king.  He is looking for anyone who was godly.  You can almost hear him pleading with Jeremiah, much like Abraham pleaded for the cities of Sodom and Gomorrah.

"Go up and down the streets of Jerusalem,
look around and consider,
search through her squares.
If you can find but one person
who deals honestly and seeks the truth,
I will forgive this city." - Jeremiah 5:1 NIV

Only one, one holy person, one person who has not bowed their knees to any other idols.  That is all it would take to spare Judah  But there were none to be found.