2 Kings 21
Manasseh's Reign (JUDAH)
Manasseh's Sin (1-6)
The most wicked of all kings was Manasseh. Born late in his father's life, Manasseh was able to lose all Hezekiah had gained—spiritual renewal, political independence, and freedom from destructive pagan practices. He came to the throne early in life and was like the spoiled son of an older father. He was quickly swayed by the wicked influences of those around him. He plainly did evil, turning Judah into a practicing pagan nation:
a) he rebuilt the shrines his father had destroyed
b) he built altars to Baal
c) he returned the Asherah pole
d) his worship madness was compared to Ahab, king of Israel
e) he bowed to the demonic forces of the heavens
f) he built altars to demonic gods in the Temple his father had restored
g) he placed alerts in the courtyards from which to worship astrological powers
h) he sacrificed his own son to Molech
i) he made a habit of participating in witchcraft, ritual demonism, superstitions, keeping track of lucky days, and calling up the dead
j) all of this led him to do much evil (1-6)
k) like carving an image of Asherah and erecting it defiantly in the Temple
Through Manasseh, Yahweh's Promises to Judah Canceled (7-15)
Yahweh had promised His presence would remain in Jerusalem forever (4) if His name would be honored and Jerusalem remain the chosen place to gather and sacrifice while the law He gave through Moses was obeyed. If these conditions were kept, then Yahweh promised they would never go into exile. But due to Manasseh's and Judah's excesses, that promise was annulled while the promise to remove them from the land was enforced (8).
Instead of following Yahweh, the people followed Manasseh who led them to do more evil and make them more wicked than the nations they had dispossessed (9).
So Yahweh raised up anonymous prophets, among them certainly Isaiah, who declared Manasseh to have been abhorrent in his actions in leading Judah to be more vile than the Amorites who God drove out before them (10-11).
God made it clear that when people would hear in the future what had happened to Judah, their ears would cringe or become struck with anxiety themselves by the severity of the news (12). Yahweh would judge Judah by the same standard he had judged Israel and Manasseh was going to be judged by the same standard Yahweh used on Ahab. Yahweh was going to wipe Jerusalem clean and then turn them their head (13). The few who would be left from the wiping out would be taken captive and treated like battle plunder. The Manasseh generation Yahweh considered to be the most detestable generation of Israeli history (15).
Manasseh's Response to the Prophetic Word (16-18)
Instead of humbling himself before the prophetic word, Manasseh worsened and began to murder innocent people who were seeking to resist him, filling Jerusalem with blood. Isaiah, no doubt with all the other anonymous prophets, being caught up in the butchery. So not only did Manasseh teach Judah how to worship false gods, but he also taught them how to murder and kill in "Hitler-esque" fashion.
Of course Manasseh did other stuff (like, according to Assyrian history, became a vassal of Assyria), meaning more and more sinning and those things are written in other places.
Interestingly, Manasseh, at the end of his life, remembered his father's faith and humility while being held in captivity by the Assyrians in Babylon. In the prison, he repented to Yahweh and then was restored to his throne. At the end of his life, scripture records that he made a valiant effort to restore Yahweh worship but in the end it would have no effect on his son (2 Chronicles 33:11-17).
Manasseh eventually died and was placed in the palace garden, a seemingly private ceremony.
Amon's Reign (19-26) (JUDAH)
Amon began to reign, and he was not moved by his father's latter years of repentance. He was evil like Manasseh was before his repentance. He could not get his raging lust out of his system, so he kept right on worshiping the idols and practicing the evil his father had done, completely abandoning Yahweh and His ways (19-23).
Some patriots to the cause of being liberated from Assyria assassinated Amon after two years of ruling in his own palace. They were mistaken to assume the assassination of the king would be met with celebration and honor. Those more powerful in Amon's government had the conspirators killed and placed his eight-year-old son on the throne in his place (24).
Of course Amon did other stuff in his short reign and it is written in other places, and he too seems to have had a private ceremony and was buried in the same palace garden his father was buried in (25).