2 Peter 2:5

“And spared not the old world, etc.] In distinction from the present world, that now is; which was, as it were, formed anew out of that which was destroyed by the deluge. The Vulgate Latin version renders it, “the original world”; and the Ethiopic version, “the first world”; it designs the ancient inhabitants of the world, as it was from the beginning, before the flood; who, being wicked, were not spared by God, but had just punishment inflicted on them: but saved Noah the eighth person; not the eighth from Adam, as Enoch is said to be the seventh from him, (<650114>Jude 1:14) for he was the tenth; nor is it to be read with the following clause, “the eighth preacher of righteousness”; but he…”

“eighth--that is, Noah, and seven others. Contrasted with the densely peopled "world of the ungodly." preacher--not only "righteous" himself (compare Pe2 2:8), but also "a preacher of righteousness": adduced by Peter against the licentiousness of the false teachers (Pe2 2:2) who have no prospect before them but destruction, even as it overtook the ungodly world in Noah's days.”

“And spared not the old world - The world before the flood. The argument here is, that he cut off that wicked race, and thus showed that he would punish the guilty. By that awful act of sweeping away the inhabitants of a world, he showed that people could not sin with impunity, and that the incorrigibly wicked must perish. But saved Noah the eighth person - This reference to Noah, like the reference to Lot in 2 Peter 2:7, seems to have been thrown in in the progress of the argument as an incidental remark, to show that the righteous, however few in number, would be saved when the wicked were cut off. The phrase “Noah the eighth,” means Noah, one of eight; that is, Noah and seven others. This…”

“And spared not the old, the antediluvian, world, but he preserved Noah the eighth person - that is, Noah and seven others, a preacher as well as practiser, of righteousness. Bringing a flood on the world of the ungodly - Whose numbers stood them in no stead. 2 Peter 2:9”

“2:5 The second example of judgment is that God did not spare the ancient world at the time of Noah. In the flood, God destroyed all human life apart from Noah and his family (see Gen 6–8).”

“spared: Gen. 6:1-8:22; Job 22:15, Job 22:16; Mat 24:37-39; Luk 17:26, Luk 17:27; Heb 11:7 the eighth: Gen. 7:1-24; Pe1 3:20 a preacher: Pe1 3:19; Jde 1:14, Jde 1:15 bringing: Pe2 3:6 2 Peter 2:6”