Albert Barnes Commentary 2 Kings 16

Ahaz was the worst of all the kings of Judah. He imitated the worst of the Israelite kings—Ahab and Ahaziah—by re-introducing the worship of Baal, which had been rooted out of Israel by Jehu and out of Judah by Jehoiada.

And made his son to pass through the fire—that is, Ahaz adopted the Moloch worship of the Ammonites and Moabites (2 Kings 3:27; Micah 6:7). He sacrificed at least one son, probably his firstborn, according to the horrid rites of those nations and the Canaanite tribes (Deuteronomy 12:31; Psalms 106:37–38).

Before this time, it seems, the Jews had been guiltless of this abomination. They had been warned against it by Moses (Deuteronomy 18:10). And if, as some think, they had practiced it in the wilderness (Ezekiel 20:26; Amos 5:26), the sin must have been rare and exceptional, for from the time they entered the promised land, they had completely put it away.

Now, however, this sin became so frequent (compare 2 Kings 17:17; 21:6) that it was met with the strongest protests from Jeremiah and Ezekiel (Jeremiah 7:31–32; Jeremiah 19:2–6; Jeremiah 32:35; Ezekiel 16:20; Ezekiel 20:26; Ezekiel 23:37).

He sacrificed ... - Other kings of Judah had allowed their people to do so. Ahaz was the first, so far as we know, to countenance the practice by his own example.

Rezin and Pekah, who had already begun their attacks upon Judea in the reign of Jotham (2 Kings 15:37), regarded the accession of a boy-king, only 16 years of age, as especially favorable to their projects and proceeded without loss of time to carry them out. The earlier scenes of the war, omitted by the writer of Kings, are given at some length in 2 Chronicles 28:5–15.

Either during the siege or after withdrawing from Jerusalem, Rezin made an expedition to the Red Sea coast and took control of the city, which had belonged to Judea for about 70 years (marginal reference). Most modern commentators render this verse as: “Rezin recovered (or restored) Elath to Edom... and the Edomites came to Elath.” Regarding the resemblance between the words Aram and Edom in the original text, see the note on 2 Samuel 8:12.

Ahaz was threatened on all sides: on the north by Rezin and Pekah, on the southeast by Edom (2 Chronicles 28:17), and on the southwest by the Philistines (2 Chronicles 28:18).

To these external dangers was added the still greater peril of disaffection at home. A large party in Judah was “weary” of the house of David (Isaiah 7:13), ready to join the confederacy (Isaiah 8:6, 8:12) and to accept “the son of Tabeal” as king. Seeing no hope of safety unless he could obtain a powerful protector, and with Egypt being particularly weak at this time, Ahaz turned to Assyria.