Read: 2 Chronicles 25-27
Marked:2 Chronicles 25:2, And he did [what was] right in the sight of the LORD, but not with a loyal heart.
Amaziah did what was right, but not with a loyal heart, or perfect, or complete heart. The Bible says the heart of man is deceitful (Jeremiah 17:9).
In Amaziah’s case, his deceitful heart lead him to worship false idols (V14) which ultimately led to military defeat (V22), imprisonment, and death at the hands of his own people.
I must guard my heart against deceit and follow God wholeheartedly, trusting in God and not my own ways.