This evaluation of Amaziah's character provides a key to understanding his character. In II Chronicles 25:11-12, a battle between Judah and Edom occurs, and Amaziah wins a great victory. Then he does something that defies logic:

Now it was so, after Amaziah came from the slaughter of the Edomites, that he brought the gods of the people of Seir, set them up to be his gods, and bowed down before them, and burned incense to them. (II Chronicles 25:14)

This reaction is hard to comprehend! God gave him a great victory over the Edomites and their gods, and instead of praising and worshipping the God of Israel, he decides to adopt the idols of Edom as his gods. What was he thinking? God responds as we might expect:

Therefore the anger of the LORD was aroused against Amaziah, and He sent him a prophet who said to him, “Why have you sought the gods of the people, which could not rescue their own people from your hand?” So it was, as he talked with him, that the king said to him, “Have we made you the king's counselor? Cease! Why should you be killed?” Then the prophet ceased and said, “I know that God has determined to destroy you because you have done this and have not heeded my advice.” (II Chronicles 25:15-16)

Amaziah would not take correction and threatened to kill God's prophet if he continued to criticize him for his actions. Though he had followed the prophet's advice earlier, the king is now beginning to expose his disloyal heart.

Feeling strong, Amaziah decides to challenge Israel, whose angry mercenaries had killed three thousand Judahites after being dismissed from Judah's service—not a very smart move. For one thing, it pitted Judah with two tribes against Israel with its ten tribes. Joash, king of Israel, was justifiably contemptuous of Amaziah's challenge, warning him of defeat in the form of a parable (II Chronicles 25:18).

Amaziah, in his pride, refuses to listen. The chronicler interjects that God inspired his refusal because He needed to punish the king for taking Edomite gods as his own (verse 20). Amaziah takes his forces into battle against Israel at Beth Shemesh, and he and his army are smashed just as the king of Israel had predicted.

Like his father Joash, Amaziah comes to a violent end years later:

After the time that Amaziah turned away from following the LORD, they [likely a group of nobles] made a conspiracy against him in Jerusalem, and he fled to Lachish; but they sent after him to Lachish and killed him there. Then they brought him on horses and buried him with his fathers in the City of Judah. (II Chronicles 25:27-28)

So, for the second time in as many generations, the king of Judah is assassinated. The conspirators held Amaziah in such contempt that they killed him, tied him over the back of a horse, and sent his body back to Jerusalem for burial. Another king suffers an ignominious end, although he at least had the honor of burial among the former kings of Judah.

In terms of character, Amaziah was unstable, reversing his early loyalty to God on a dime. He wanted victory and glory, and when God gave it to him, he failed to see that God was its source and absurdly chose to worship Edomite gods. Instead of listening to God's prophet, he threatened him with death. He foolishly challenged a far stronger Israelite army, expecting the same results he had had against the Edomites, not realizing the Source of his power had become his adversary. And apparently, he never learned his lesson, disenchanting his nobles until they decided to rid themselves of him.

We could compare him to the man in Jesus' parable (Luke 14:28-30), who began to build, seemingly well. However, his early success went to his head, and like a piece of overripe fruit, he began to turn rotten. He dropped the true God for idols. Like the man in the parable, he did not have what it took to finish what he had started.

Unsteady in character and conduct, he was a semi-religious man who only wanted what faithfulness could get him. He was sufficiently pious early in life, but that early piety did not justify his later pride and self-indulgence.