John Calvin Commentary 2 Peter 2:12

"But these, as creatures without reason, born mere animals to be taken and destroyed, railing in matters whereof they are ignorant, shall in their destroying surely be destroyed," — 2 Peter 2:12 (ASV)

But these. He proceeds with what he had begun to say regarding impious and wicked corrupters. And, first, he condemns their loose morals and the obscene wickedness of their whole life; and then he says that they were audacious and perverse, so that by their scurrilous talkativeness they insinuated themselves into the favor of many.

He especially compares them to those brute animals, which seem to have come into existence to be ensnared, and to be driven to their own ruin by their own instinct; as if he had said, that not being enticed by any allurements, they themselves hasten to throw themselves into the snares of Satan and of death. For what we translate, naturally born, Peter has literally, “natural born.” But there is not much difference in meaning, whether one of the two has been supplied by someone else, or whether by writing both he meant to express his meaning more fully.

What he adds, speaking evil of the things that they understand not, refers to the pride and presumption he mentioned in the preceding verse. He then says that all excellence was insolently despised by them, because they had become entirely stupefied, so that they were no different from beasts. But the word I have translated as 'destruction,' and subsequently as 'corruption,' is the same word, φθορὰ; it is, however, understood in various ways. But when he says that they would perish in their own corruption, he shows that their corruptions would be ruinous or destructive.