2 Kings 16:3
But he walked in the way of the kings of Israel, yea, and made his son to pass through the fire, according to the abominations of the heathen, whom the LORD cast out from before the children of Israel.
But he walked in the way of the kings of Israel..... Worshipping the calves as they did; which, as it was contrary to the religious sentiments in which he was educated, so against his political interest, which was the only, or at least the principal thing, which swayed with the kings of Israel to continue that idolatry:
yea, and made his son to pass through the fire; between two fires to Molech, by way of lustration; which might be true of Hezekiah his son, and others of his sons, for he had more he burnt with fire, as appears from 2 Chronicles 28:3, both ways were used in that sort of idolatry,
See Gill on "Leviticus 18:21",
according to the abominations of the heathen, whom the LORD cast out from before the children of Israel; the old Canaanites; so the Carthaginians, a colony of the Phoenicians, used in time of calamity to offer human sacrifices, and even their children, to appease their deities {l}. Theodoret says, he had seen in some cities, in his time, piles kindled once a year, over which not only boys, but men, would leap, and infants were carried by their mothers through the flames; which seemed to be an expiation or purgation, and which he takes to be the same with the sin of Ahaz.
{l} Justin. e Trogo, Hist. l. 18. c. 6. Curt. Hist. l. 4. c. 3. Pescennius Festus apud Lactant. de fals. Relig. l. 1. c. 21.