John Calvin Commentary Hebrews 4:1

"Let us fear therefore, lest haply, a promise being left of entering into his rest, any one of you should seem to have come short of it." — Hebrews 4:1 (ASV)

Let us therefore fear, etc. He concludes that there was reason to fear, so that the Jews to whom he was writing might not be deprived of the blessing offered to them. And then he says, for fear that anyone, suggesting that it was his anxious desire to lead them, one and all, to God.

For it is the duty of a good shepherd, in watching over the whole flock, to care for every sheep in such a way that no one might be lost. Indeed, we ought also to feel for one another in such a way that everyone should fear for his neighbors as well as for himself.

But the fear which is recommended here is not that which shakes the confidence of faith, but is such as fills us with such concern that we do not become sluggish with indifference. Let us then fear—not that we ought to tremble or to entertain distrust as if uncertain about the outcome—but so that we are not unfaithful to God’s grace.

By saying, Lest we fall short of the promise left to us, he implies that no one falls short of it except the one who, by rejecting grace, has first renounced the promise. For God is so far from changing His mind about doing us good that He does not cease to bestow His gifts, except when we despise His calling. The inferential word therefore, or then, means that by the fall of others we are taught humility and watchfulness, according to what Paul also says:

These through unbelief have fallen; do not then be high-minded, but fear (Romans 11:20).