en_tn/2ch/28/23.md

the gods of Damascus

The Syrians believed Damascus to be the city where their gods dwelt, much like Yahweh dwelt in Jerusalem. Alternate translation: "the gods whom the Syrians worshiped in Damascus" (See: rc://en/ta/man/translate/figs-explicit)

gods that had defeated him

This expresses Ahaz's opinion. Because the Syrians had defeated him and his army, Ahaz attributed his defeat to the gods whom the Syrians worshiped. Alternate translation: "gods whom he believed had enabled the Syrian army to defeat him" (See: rc://en/ta/man/translate/figs-explicit)

they were the ruin of him and of all Israel

The word "ruin" can be translated with a verb. Alternate translation: "those gods ruined him and all Israel" (See: rc://en/ta/man/translate/figs-abstractnouns)

all Israel

Here "Israel" represents the southern kingdom of Judah.