Amaziah's Reign and War With Israel
Like so many people, Amaziah, king of Judah, started off on the right track, but his initial acts soon faded away. Indeed, it is specifically mentioned that he did "everything as his father Joash had done" (2 Kings 14:3 2 Kings 14:3And he did that which was right in the sight of the LORD, yet not like David his father: he did according to all things as Joash his father did.
American King James Version×)—meaning that he followed the right example that Joash set early on. But he later follows the example of Joash in apostasy and resultant disaster.
His first action as king was to execute those who had murdered his father (2 Chronicles 24:25-26 2 Chronicles 24:25-26  And when they were departed from him, (for they left him in great diseases,) his own servants conspired against him for the blood of the sons of Jehoiada the priest, and slew him on his bed, and he died: and they buried him in the city of David, but they buried him not in the sepulchers of the kings.
 And these are they that conspired against him; Zabad the son of Shimeath an Ammonitess, and Jehozabad the son of Shimrith a Moabitess.
American King James Version×). In doing so, he followed what God had taught Israel through Moses by not killing the sons of the perpetrators for their fathers' crime (compare Deuteronomy 24:16 Deuteronomy 24:16The fathers shall not be put to death for the children, neither shall the children be put to death for the fathers: every man shall be put to death for his own sin.
American King James Version×).
Then, however, we see Amaziah starting to waver. Instead of relying on God (2 Chronicles 14:11 2 Chronicles 14:11And Asa cried to the LORD his God, and said, LORD, it is nothing with you to help, whether with many, or with them that have no power: help us, O LORD our God; for we rest on you, and in your name we go against this multitude. O LORD, you are our God; let no man prevail against you.
American King James Version×; Jeremiah 17:5 Jeremiah 17:5Thus said the LORD; Cursed be the man that trusts in man, and makes flesh his arm, and whose heart departs from the LORD.
American King James Version×), he thought he could protect Judah by hiring mercenaries from Ephraim—but God is not limited to our human efforts (Mark 9:23 Mark 9:23Jesus said to him, If you can believe, all things are possible to him that believes.
American King James Version×). To his credit, Amaziah listened to a man of God who came to him with sound advice (2 Chronicles 25:7-10 2 Chronicles 25:7-10  But there came a man of God to him, saying, O king, let not the army of Israel go with you; for the LORD is not with Israel, to wit, with all the children of Ephraim.  But if you will go, do it; be strong for the battle: God shall make you fall before the enemy: for God has power to help, and to cast down.  And Amaziah said to the man of God, But what shall we do for the hundred talents which I have given to the army of Israel? And the man of God answered, The LORD is able to give you much more than this.  Then Amaziah separated them, to wit, the army that was come to him out of Ephraim, to go home again: why their anger was greatly kindled against Judah, and they returned home in great anger.
American King James Version×). God honored his obedience with victory—but his earlier lack of trust was to backfire on him. The mercenaries he dismissed took advantage of the armies being away and pillaged Judah's frontier towns.
Sadly, it all went downhill from there. At this point, Chronicles records an utterly unconscionable fact not mentioned in Kings. Instead of thanking God for his victory, Amaziah "brought the gods of the people of Seir [that is, of the Edomites, whom he'd just defeated], set them up to be his gods, and bowed down before them and burned incense to them" (2 Chronicles 25:14 2 Chronicles 25:14Now it came to pass, after that Amaziah was come from the slaughter of the Edomites, that he brought the gods of the children of Seir, and set them up to be his gods, and bowed down himself before them, and burned incense to them.
American King James Version×). This was totally irrational to the point of absurdity. "The futility of 'gods, which could not save their own people' should have been obvious, but men still worship that which is demonstrably inadequate"(Expositor's Bible Commentary, note on verse 15, emphasis added). It seems that Amaziah couldn't learn the lesson.
There was no way God would allow Amaziah to get away with such outrageous behavior, and He sent a prophet to correct the king. But Amaziah didn't want the advice. Rather, he became a victim of his own pride. Overconfident following his victory over the Edomites, and angry at the Israelite mercenaries who raided Judah's cities after his dismissal of them, Amaziah challenged Jehoash of Israel to a battle—a senseless undertaking as portrayed by Jehoash's fable, where he likens Amaziah to a thistle fighting a cedar of Lebanon. Yet Amaziah would not see reason—indeed, this development "came from God," we are told, as a way for Him to impose judgment (verse 20).
Judah lost the battle. And, more humiliating still, Amaziah was taken captive and treasures from the temple and the palace were taken as spoils of war. Biblical historian Eugene Merrill writes: "Amaziah himself narrowly escaped with his life. Why Jehoash spared him at all is a mystery, for he evidently took him back to Samaria as a prisoner (2 Kings 14:13-14 2 Kings 14:13-14  And Jehoash king of Israel took Amaziah king of Judah, the son of Jehoash the son of Ahaziah, at Bethshemesh, and came to Jerusalem, and broke down the wall of Jerusalem from the gate of Ephraim to the corner gate, four hundred cubits.
 And he took all the gold and silver, and all the vessels that were found in the house of the LORD, and in the treasures of the king's house, and hostages, and returned to Samaria.
American King James Version×) [after taking him to the plunder of Jerusalem (2 Chronicles 25:23-24 2 Chronicles 25:23-24  And Joash the king of Israel took Amaziah king of Judah, the son of Joash, the son of Jehoahaz, at Bethshemesh, and brought him to Jerusalem, and broke down the wall of Jerusalem from the gate of Ephraim to the corner gate, four hundred cubits.  And he took all the gold and the silver, and all the vessels that were found in the house of God with Obededom, and the treasures of the king's house, the hostages also, and returned to Samaria.
American King James Version×)]. The answer may lie in the date of these events. Both the author of Kings and the chronicler stress that Amaziah outlived Jehoash by fifteen years (2 Kings 14:17 2 Kings 14:17And Amaziah the son of Joash king of Judah lived after the death of Jehoash son of Jehoahaz king of Israel fifteen years.
American King James Version×; 2 Chronicles 25:25). This may be their oblique way of suggesting that Amaziah's release from Israelite control is to be tied in with the death of his captor" (Kingdom of Priests: A History of Old Testament Israel, 1987, p. 372). Merrill's explanation has Amaziah being released soon afterward—seeing the battle described here as occurring just before Jehoash's death. However, he also offers the possibility that the battle occurred 10 years prior to Jehoash's death (see p. 372 footnote).
In comparing all the biblical data on when the kings of this period reigned, the latter appears to be the case. This would mean that Amaziah was a captive of Israel for 10 years, during which time his son Uzziah (or Azariah) was elevated to the throne of Judah. Upon the death of Jehoash, Amaziah is evidently permitted to return to Judah, where he lives for 15 more years in a coregency with his son (see Edwin R. Thiele, The Mysterious Numbers of the Hebrew Kings,1983, pp. 113-116).