Charles Spurgeon Commentary 2 Chronicles 28:1-2

"Ahaz was twenty years old when he began to reign; and he reigned sixteen years in Jerusalem: and he did not that which was right in the eyes of Jehovah, like David his father; but he walked in the ways of the kings of Israel, and made also molten images for the Baalim." — 2 Chronicles 28:1-2 (ASV)

But he did not that which was right in the sight of the LORD, like David his father: for he walked in the ways of the kings of Israel,

They had set up the worship of God under emblems. There were the calves of Bethel, which represented strength. This was the worship of God by imagery, and Ahaz imitated it, and went even further in sin.