John Calvin Commentary Exodus 15:2

"Jehovah is my strength and song, And he is become my salvation: This is my God, and I will praise him; My father`s God, and I will exalt him." — Exodus 15:2 (ASV)

The Lord is my strength. In this expression, they acknowledge that they have a sufficient defense in God. 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; therefore, it is not lawful to glory except in God alone.

But we must observe that the help of God is connected with His praise, because this is the goal of all His benefits: that we should regard our salvation as received from Him. This is mentioned here in the third place. For to say that God had “become their salvation” was equivalent to saying 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 harsh, 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 is ready to destroy whatever lifts itself up against Him.