2:22 The dog . . . the sow. In contrast to the modern view of dogs as “man’s best friend,” the ancient Jews despised them (Ex. 22:31; Prov. 26:11; Rev. 22:15). Swine were avoided as unclean (Lev. 11:7; Is. 65:4). Peter’s point is that mere religious profession or even outward change does not change a person’s heart. The apostasy of the false teachers reveals their true nature.