John Calvin Commentary Genesis 18:15

"Then Sarah denied, saying, I laughed not; for she was afraid. And he said, Nay; but thou didst laugh." — Genesis 18:15 (ASV)

Then Sarah denied. Another sin of Sarah’s was that she endeavored to cover and hide her laughter by a falsehood. Yet this excuse did not proceed from obstinate wickedness, as hypocrites are accustomed to snatch at subterfuges, so that they remain as they are, even to the end.

Sarah’s feelings were of a different kind. For while she repents of her own folly, she is still so terrified that she denies she had done what she now perceives to be displeasing to God. From this we infer how great the corruption of our nature is, which causes even the fear of God—the highest of all virtues—to degenerate into a fault.

Moreover, we must observe from where that fear, of which Moses makes mention, suddenly entered Sarah’s mind: namely, from the realization that God had detected her secret sin. We see, therefore, how the majesty of God, when we seriously feel it, shakes us out of our insensibility. We are especially compelled to feel this way when God ascends His tribunal and brings our sins to light.

Nay; but thou didst laugh. The angel does not contend with a multiplicity of words but directly refutes her false denial of the fact. From this we may learn that we gain no advantage by evasion when the Lord reproves us, because He will immediately dispatch our case with a single word.

Therefore, we must beware lest we imitate the petulance of those who mock God with false pretenses and eventually rush into gross contempt of Him. However He may seem to leave us unnoticed for a time, yet He will fulminate against us with that terrible voice, “It is not as you pretend.” In short, it is not enough that the judgment of God should be reverenced, unless we also confess our sins sincerely and without deceptions or evasions.

For a double condemnation awaits those who, from a desire to escape the judgment of God, take refuge in deceit. We must, therefore, bring a sincere confession so that, as persons openly condemned, we may obtain pardon. But since God was content with giving a friendly rebuke, and did not more severely punish Sarah’s double offense, from this we perceive with what tender indulgence He sometimes regards His own people.

Zacharias was more severely treated, as he was struck mute for nine months (Luke 1:9). But it is not for us to prescribe a perpetual law to God, who, as He generally brings His own people to repentance by punishments, often sees fit to humble them sufficiently without inflicting any chastisement.

In Sarah, truly, He gives a singular instance of His compassion: He freely forgives her all and still chooses that she should remain the mother of the Church. In the meantime, we must observe how much better it is that we should be brought before Him as guilty and, like convicted persons, be silent, than that we should delight ourselves in sin, as a great part of the world is accustomed to do.