2 Chronicles 25:2 - "He did what was right in the eyes of the Lord, but not wholeheartedly."
When Amaziah became king, he continued in his father's pattern. He executed those who had assassinated his father. He kept alive an appearance of attentiveness to God, but his heart wasn't in it. His early successes, which could have inspired humility, instead gave rise to arrogance. He received but rejected God's warnings. He challenged a reluctant Israel to a military confrontation. God ensured a humiliating defeat for Amaziah and Judah. The remainder of Amaziah's reign was a road to destruction. Amaziah's own people plotted and killed their king.
Despite an impressive start, King Amaziah’s end was not so wonderful. In arrogance, he challenged Israel to battle, lost miserably, and saw the temple depleted of its riches. Eventually he was forced from Jerusalem and killed by conspirators. The king had a godly start that ended in misery and defeat.
Noting this king's life, we should be compelled to examine our own lives. Are we offering our service to God with imperfect hearts? The downfall of Amaziah should encourage all of us to examine our service constantly for signs of an “imperfect heart.” Remember that Amaziah did some right things and yet his end was destruction.