John Calvin Commentary 2 Peter 2:9

"the Lord knoweth how to deliver the godly out of temptation, and to keep the unrighteous under punishment unto the day of judgment;" — 2 Peter 2:9 (ASV)

The Lord knows. What first troubles the weak is that when the faithful anxiously seek aid, they are not immediately helped by God. On the contrary, He sometimes allows them, as it were, to pine away through daily weariness and listlessness. Secondly, it troubles them when the wicked behave recklessly with impunity, and God in the meantime is silent, as though He secretly allowed their evil deeds.

Peter now removes this double difficulty, for he testifies that the Lord knows when it is suitable to deliver the godly from temptation. By these words, he reminds us that this role ought to be left to Him. Therefore, we ought to endure temptations and not lose heart whenever He defers His vengeance against the ungodly.

This consolation is very necessary for us, for this thought is apt to creep in: “If the Lord wanted His own to be safe, why does He not gather them all into some corner of the earth, so that they may mutually encourage one another to holiness? Why does He mingle them with the wicked, by whom they may be defiled?”

But when God claims for Himself the responsibility of helping and protecting His own, so that they may not fail in the contest, we gather courage to fight more strenuously. The meaning of the first clause is that this principle is prescribed by the Lord to all the godly: they are to be tested by various temptations, but they are to maintain good hope of success, because they are never to be deprived of His aid and help.

And to reserve the unjust. By this clause, he shows that God so regulates His judgments as to bear with the wicked for a time, but not to leave them unpunished. Thus he corrects excessive haste, by which we are accustomed to be carried headlong, especially when the atrocity of wickedness grievously wounds us, for we then wish God to fulminate without delay. When He does not do so, He seems no longer to be the judge of the world. So that this temporary impunity of wickedness does not disturb us, Peter reminds us that a day of judgment has been appointed by the Lord, and that, therefore, the wicked shall by no means escape punishment, though it is not immediately inflicted.

There is an emphasis in the word reserve, as though he had said that they shall not escape the hand of God but be held bound, as it were, by hidden chains, so that they may at a certain time be brought forth to judgment. The participle κολαζομένους, though in the present tense, is nevertheless to be explained in this way: that they are reserved or kept to be punished, or so that they may be punished. For he instructs us to rely on the expectation of the last judgment, so that in hope and patience we may fight until the end of life.