72. And the second time he denied with an oath. It deserves attention, that Peter, after finding that he could not escape by a simple denial, doubles his crime by adding an oath; and a little after, when he is still more vehemently pressed, he proceeds even to cursing. Hence we infer that a sinner, after having once fallen, is always hurried on from bad to worse; so that those who begin with ordinary offenses afterwards rush headlong into the basest crimes, from which at first they would have recoiled with horror. And this is the just vengeance of God, after we have deprived ourselves of the assistance of the Holy Spirit, to allow Satan a violent exercise of power over us, that, having subdued and made us his slaves, he may drive us wherever he pleases. But this happens chiefly in a denial of the faith; for when a man, through fear of the cross, has turned aside from a pure profession of the gospel, if he perceive that his enemies are not yet satisfied, will proceed farther, and what he had not ventured fully to acknowledge he denies flatly with an oath, and without any ambiguity of words.
We ought also to observe, that almost in a single moment Peter thrice gave way; for this shows how unsteady we are, and how liable to fall, whenever Satan drives us. Certainly we shall never cease to fall, if the Lord do not stretch out his hand to uphold us. When the rigor of the grace of Christ was extinguished in Peter, whoever might afterwards meet hit and interrogate him about Christ, he would have been ready to deny a hundred or a thousand times. Although, then, it was very base in him to fall thrice, yet the Lord spared him by restraining the tongues of enemies from making additional attacks upon him. Thus, also, it is every day necessary for the Lord to bridle Satan, lest he overwhelm us with innumerable temptations; for though he does not cease to employ many instruments in assailing us, were it not that the Lord, paying regard to our weakness, restrains the violence of his rage, we would have to contend against a prodigious amount of temptations. In this respect, therefore, we ought to praise the mercy of the Lord, who does not permit our enemy to make advances against us, almost the hundredth part of what he would desire.