2. The Lord is my strength. In this expression they acknowledge that they have a sufficient defense in God; and afterwards they add, that His grace furnishes them with just ground for praise. The sum is, that they were strong in God, and had not conquered their enemies by their own bravery; and that, therefore, it is not lawful to glory save in God alone. But we must observe that the help of God is conjoined with His praise, because this is the end of all His benefits, that we should hold our salvation as received from Him, which is here mentioned in the third place, for to say that God had “become their salvation,” was as much as to say that the people were saved by His grace. In the second clause there is an antithesis between the true God and all false ones; for there is much emphasis in the declaration, “he is my God,” as by it Moses excludes all that multitude of gods which then were everywhere worshipped in the world. To the same effect he adds, “my father’s God,” thus distinguishing the faith of Abraham from all the superstitions of the Gentiles. The faithful then declare that it is safe for them to repose in this One God, and that His praises are worthy of celebration. Isaiah imitates this figure. Isaiah 25:9,
“Lo, this is our God; we have waited for him, and he will save us: this is the Lord; we have waited for him.”
What follows in the next verse — “The Lord is a man of war,” is to the same purpose, for although at first sight the phrase may seem a harsh one, still it is not without beauty: that God is armed in military attire, to contend with all the forces of His foes. Therefore, says Moses, the name of the Lord belongs to Him alone, because His hand awaits to destroy whatever lifts itself up against Him.