We have here a general character of the reign of Ahaz. Few and evil were his days - few, for he died at thirty-six - evil, for we are here told, 1. That he did not that which was right like David (Kg2 16:2), that is, he had none of that concern and affection for the instituted service and worship of God for which David was celebrated. He had no love for the temple, made no conscience of his duty to God, nor had any regard to his law. Herein he was unlike David; it was his honour that he was of the house and lineage of David, and it was owing to God's ancient covenant with David that he was now upon the throne, which aggravated his wickedness; for he was a reproach to that honourable name and family, which therefore was really a reproach to him (Degeneranti genus opprobrium - A good extraction is a disgrace to him who degenerates from it), and though he enjoyed the benefit of David's piety he did not tread in the steps of it. 2. That he walked in the way of the kings of Israel (Kg2 16:3), who all worshipped the calves. He was not joined in any affinity with them, as Jehoram and Ahaziah were with the house of Ahab, but, ex mero motu - without any instigation, walked in their way. The kings of Israel pleaded policy and reasons of state for their idolatry, but Ahaz had no such pretence: in him it was the most unreasonable impolitic thing that could be. They were his enemies, and had proved enemies to themselves too by their idolatry; yet he walked in their way. 3. That he made his sons to pass through the fire, to the honour of his dunghill-deities. He burnt them, so it is expressly said of him (Ch2 28:3), burnt some of them, and perhaps made others of them (Hezekiah himself not excepted, though afterwards he was never the worse for it) to pass between two fires, or to be drawn through a flame, in token of their dedication to the idol. 4. That he did according to the abominations of the heathen whom the Lord had cast out. it was an instance of his great folly that he would be guided in his religion by those whom he saw fallen into the ditch before his eyes, and follow them; and it was an instance of his great impiety that he would conform to those usages which God had declared to be abominable to him, and set himself to write after the copy of those whom God had cast out, thus walking directly contrary to God. 5. That he sacrificed in the high places, Kg2 16:4. If his father had but had zeal enough to take them away, the debauching of his sons might have been prevented; but those that connive at sin know not what dangerous snares they lay for those that come after them. He forsook God's house, was weary of that place where, in his father's time, he had often been detained before the Lord, and performed his devotions on high hills, where he had a better prospect, and under green trees, where he had a more pleasant shade. It was a religion little worth, which was guided by fancy, not by faith.

Twenty years old was Ahaz - Here is another considerable difficulty in the chronology. Ahaz was but twenty years old when he began to reign, and he died after he had reigned sixteen years; consequently his whole age amounted only to thirty-six years. But Hezekiah his son was twenty-five years old when he began to reign; and if this were so, then Ahaz must have been the father of Hezekiah when he was but eleven years of age! Some think that the twenty years mentioned here respect the beginning of the reign of Jotham, father of Ahaz; so that the passage should be thus translated: Ahaz was twenty years of age when his father began to reign; and consequently he was fifty-two years old when he died, seeing Jotham reigned sixteen years: and therefore Hezekiah was born when his father was twenty-seven years of age. This however is a violent solution, and worthy of little credit. It is better to return to the text as it stands, and allow that Ahaz might be only eleven or twelve years old when he had Hezekiah: this is not at all impossible; as we know that the youth of both sexes in the eastern countries are marriageable at ten or twelve years of age, and are frequently betrothed when they are but nine. I know a woman, an East Indian, who had the second of her two first children when she was only fourteen years of age, and must have had the first when between eleven and twelve. I hold it therefore quite a possible case that Ahaz might have had a son born to him when he was but eleven or twelve years old.

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 Ch2 28:3, both ways were used in that sort of idolatry; see Gill on Lev 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.