John Calvin Commentary Psalms 33:21

"For our heart shall rejoice in him, Because we have trusted in his holy name." — Psalms 33:21 (ASV)

Surely our heart shall rejoice in him. As the particle כי, ki, which is twice used in this verse, has various meanings in Hebrew, it may be understood in a twofold sense here. If we interpret it affirmatively in both clauses, the meaning will be that believers glory both in their joy and in their hope.

Nor do I think it improper that these two should be referred to distinctly in the same context in this way: Surely God shall always be our joy; surely his holy name shall be like an impregnable fortress for our refuge. Why is it that believers continue persistently to call upon God, but because, satisfied with his favor, they always have, amid their sorrows and griefs, this comfort, which is sufficient to maintain their cheerfulness?

Justly, therefore, do believers affirm, in the first place, that their heart rejoices in the Lord; because, freed from wandering after the fascinations of the world, they neither waver nor hesitate at every change of fortune, but place the whole blessedness of their life in enjoying the free and fatherly favor of God.

They afterwards add, in the second place, that they trust in his holy name. If anyone, however, chooses to understand the particle כי, ki, as meaning because, assigning a cause or reason, the meaning will be expressed just as properly and elegantly in this way: Because our hope is fixed on God, he will be equally ready on his part to provide us with continual cause for joy.

And experience undoubtedly proves that when people are overwhelmed with sorrow, and pine away with care, grief, and anxiety, it is then that they may receive the consequence of their folly; since they find nothing more difficult than to set their hopes on God alone, and not to exult in their own deceitful imaginations, with which they please themselves.