In Isaiah, chapter fifty-nine, verses seventeen through eighteen, ” For he put on righteousness as a breastplate, and an helmet of salvation upon his head; and he put on the garments of vengeance for clothing, and was clad with zeal as a cloak.
According to their deeds, accordingly he will repay, fury to his adversaries, recompence to his enemies; to the islands he will repay recompence.”
Two phrases from this verse in this description of the believer’s armour: “breastplate of righteousness” and “the helmet of salvation,” as in Ephesians six, verses fourteen to seventeen. Isaiah’s mention of “garments of salvation” and “fury to his adversaries” envisions God’s great day of wrath at the end of the age.
For He put on righteousness as a breast-plate: God, resolving to appear as a man of war, puts on His armour; he calls righteousness His breast-plate, to show the justness of His cause, as also His faithfulness in making good His promises. And a helmet of salvation upon his head as the breast-plate is to defend the heart, whereby God signifies the justness of His cause, and His faithfulness; So the helmet is to defend the head, the fountain of knowledge and wisdom, and therefore by this piece of armour God would have us to know that He can neither be deceived nor disappointed to the execution of His designs, for the salvation of His faithful and obedient people; but will, without fail, carry them into effect. And He put on the garments of vengeance — Or garments made of vengeance: as God is said to put on the former for their sakes whom He would preserve, so he puts on these for their sakes whom He will destroy, namely, His people’s enemies for His own honour, and for His people’s welfare. The sum of all these expressions is to describe both the cause and effect together; the cause was righteousness and zeal in God; the effect, salvation to his people, and vengeance on His enemies.