In II Kings 14 Amaziah king of Judah is portrayed as a son of Yahweh who does what is "right in the eyes of Yahweh," his Heavenly Father (v. 3), even though, sadly, "yet not like David his father," for it says that under Amaziah "the high places were not removed; the people still sacrificed and made offerings on the high places" (v. 4).
Nevertheless Amaziah is a valiant warrior of Yahweh, and Yahweh gives him strength to defeat His enemies. Amaziah strikes down 10,000 Edomites, and even the Edomite stronghold of Sela "by storm" (v. 7). In his zeal he then turns to taunt his brother, northern Israel, "face to face" (v. 8). This leads to an interesting and unexpected turn of events, considering that not every southern king does what is right in the eyes of Yahweh, and Yahweh had clearly provided a great victory for Amaziah.
The northern king, Jehoash, reminds Amaziah that he is a "thistle" in Lebanon in comparison to the northern "cedar" kingdom, and therefore is outmatched (vv. 9-10). Then we read: "But Amaziah would not listen" (v. 11). Up next, a battle between brothers ensues and Yahweh does not defend Amaziah for covering up his ears. Judah gets defeated in battle, Amaziah is captured, 400 cubits of Jerusalem's wall are broken down, and all the gold, silver, and holy "vessels" of Yahweh's house are plundered (vv. 11-14). Amaziah did that which was right in the sight of Yahweh, until his heart was lifted up against his brother. His zeal lacked wisdom from above, and wisdom from below divided the kingdom even further.
At the very beginning of Yahweh's division of the kingdom He promised a faithful remnant in Judah for His name's sake, and even a future deliverer --Josiah by name-- to begin restoring unity (I Kng. 13:2). All throughout the books of Kings we find brother fighting against brother, and foolish zeal followed by even more foolish zeal, as the people await deliverance from God. Only the wise in heart await deliverance from Yahweh, for He is the only living and true God. As the people await deliverance from Yahweh, one of the dominant lessons to be learned is that brothers warring against brothers only divides the kingdom further and further. When Israel attacks Judah, he plunders Yahweh's house, thereby provoking brother Judah. When Judah minds his own business, Yahweh protects him, which provokes brother Israel to jealousy. But brother Judah isn't perfect either. He too never completely removes the "high places" in his midst, which we know displeases Yahweh time and time again (I Kng. 15:14; 22:43; II Kng. 12:3; 14:4). If not for Yahweh's faithfulness to the covenant He established, even Judah would be toast. But Yahweh is faithful and gracious, slow to anger and abundant in lovingkindness, forgiving iniquity and transgression (Num. 14:18; Psa. 103:8; 145:8; Joel 2:13); therefore a faithful remnant will be preserved by Him as promised.
What we learn from II Kings 14 is that instead of presuming that Yahweh would defend his zealous and courageous taunts against his brother, Amaziah should have focused his energy on the high places in his own land, the land which Yahweh had given him. Instead of attempting to defend the name of Yahweh by attacking the idols of his brother's house, he should have listened to the practical advise of his brother and remained content with his glory, stay at home, and not provoke northern Israel any further (v. 10). Amaziah should have taken this very clear hint as being providential from Yahweh, and then turn his attention to his own house; but as we know from history, he didn't. Yahweh gave Amaziah a taste of glory when he struck down the stronghold of Edom "by storm," but not even a peep of thunder is directed at the idolatrous high places of his own house; therefore when Amaziah attacked the stronghold of his brother's house, Yahweh by no means cleared the guilty (Num. 14:18), and consequently the taste of Yahweh's glorious house went with him to the northern kingdom, where he was taken captive (vv. 11-14). Perhaps if Amaziah had dealt with the idols of his own house first, pulling the log out of his own eye first, he could have seen how much his zeal lacked wisdom; then Yahweh would have honored his zeal for His house.