John Calvin Commentary Psalms 18:2

"Jehovah is my rock, and my fortress, and my deliverer; My God, my rock, in whom I will take refuge; My shield, and the horn of my salvation, my high tower." — Psalms 18:2 (ASV)

Jehovah is my rock, etc. When David thus heaps together many titles with which to honor God, it is not a useless or unnecessary accumulation of words. We know how difficult it is for people to keep their minds and hearts steadfast in God. They either imagine that having God on their side is not enough, and consequently, are always seeking support and help elsewhere, or, at the first temptation that assails them, lose the confidence they placed in him.

David, therefore, by attributing to God various methods of saving his people, declares that, provided he has God as his protector and defender, he is effectively fortified against all peril and assault. It is as if he had said, "Those whom God intends to help and defend are not only safe from one kind of danger, but are, as it were, surrounded by impregnable ramparts on all sides, so that, if a thousand deaths were presented to their view, they should not be afraid even of this formidable array."

We see, then, that David's purpose here is not only to celebrate the praises of God, as a sign of his gratitude, but also to fortify our minds with a firm and steadfast faith. This is so that, whatever afflictions befall us, we may always turn to God, and may be fully persuaded that he has the strength and power to assist us in different ways, according to the different methods of doing us harm that the wicked devise.

Nor, as I have observed before, is it without cause that David insists so much on this point and expresses the same thing in different terms. God may have aided us in one way, and yet whenever a new storm arises, we are immediately struck with terror, as if we had never experienced any of his aid.

And those who in one trouble expect protection and help from him, but who afterwards limit his power, considering it limited in other respects, act like a man who, upon going into battle, considers his chest well secured because he has a breastplate and a shield to defend him, and yet is afraid for his head, because he is without a helmet.

David, therefore, here furnishes the faithful with a complete suit of armor, so that they may feel that they are in no danger of being wounded, provided they are shielded by the power of God. That this is his purpose is apparent from the declaration he makes of his confidence in God: I will trust in him. Let us, therefore, learn from his example to apply to our own use those titles that are here attributed to God, and to apply them as an antidote against all the perplexities and distresses that may assail us. Or rather, let them be deeply imprinted on our memory, so that we may be able at once to repel whatever fear Satan may suggest to our mind.

I give this exhortation, not only because we tremble under the calamities with which we are currently assailed, but also because we groundlessly conjure up in our own imaginations dangers concerning the future, and thus needlessly trouble ourselves with the mere creations of fancy. In the song, as recorded in 2 Samuel 22:3, instead of these words, My God, my rock, it is, God of my rock. And after the word refuge, there is, My fortress, my savior, thou shalt preserve me from violence; words that make the sentence fuller, but the meaning amounts to the same thing.