2 Peter 2:6

On account of his hospitality and godliness, Lot was saved out of Sodom when all the country round was punished by means of fire and brimstone, the Lord thus making it manifest that He does not forsake those that hope in Him, but gives up such as depart from Him to punishment and torture. [Genesis 19:15-26, 2 Peter 2:6-9] For Lot's wife, who went forth with him, being of a different mind from himself, and not continuing in agreement with him [as to the command which had been given them], was made an example of, so as to be a pillar of salt unto this day. This was done that all might know that those who are of a double mind, and who distrust the power of God, bring down judgment on themselves and become a sign to all succeeding generations.

Lot, withal, the brother of Abraham, proves that it was for the merits of righteousness, without observance of the law, that he was freed from the conflagration of the Sodomites.

Do you want to know why these things happened? There was one sin which was more wicked and disgusting than any other which those people were committing. It was because of that that God gave them this judgment.

Here is proof that all the ungodly will be punished. For Peter goes over the examples of Sodom and Gomorrah so that anyone who sees this will not behave wickedly, knowing that if he does so he will suffer the same kind of punishment as they did.

God wished to proclaim the judgment that is to come when he sent fiery death from heaven upon a wicked people, setting an example for those who desire to lead wicked lives.

And the cities of Sodom and Gomorrah, etc. Because he asserts that the cities of the impious were reduced to ashes, it should be understood in two ways. Because first, through fire, he reduced them along with the adjacent lands to ashes, and when he afterwards covered the places of the fire with the waters of the Dead Sea, he still wanted to preserve the surrounding region as a specimen of ancient punishment. For very beautiful fruits indeed grow, which also generate a desire to eat for those who see them. If you pluck them, they crumble and dissolve into ashes, and raise smoke, as if they still burned. Hence, in the Book of Wisdom it is said: "This [fire] rescued the righteous man fleeing from the wicked who were perishing as the fire descended upon Pentapolis." As a testimony to whose wickedness, it is evident that a scorched earth remains deserted, and at certain times the trees have fruit (Wis. X). It can be understood: And they also remain deserted and scorched. And this is what is also added here:

For if God did not spare the angels who sinned, but cast them into chains of gloomy Tartarus10, delivering them to be kept for judgment; and did not spare the ancient world, but preserved Noah, the eighth person, a preacher of righteousness, when he brought a flood upon the world of the ungodly; and condemned the cities of Sodom and Gomorrah to destruction, reducing them to ashes, making them an example to those who afterward would live ungodly; and delivered righteous Lot, who was oppressed by the filthy conduct of the wicked—for that righteous man, dwelling among them, tormented his righteous soul from day to day by seeing and hearing their lawless deeds.
For if God did not spare the angels who sinned, nor the ancient world, but condemned the cities of Sodom and Gomorrah to destruction, reducing them to ashes, and made them an example of what is going to happen to the ungodly; indeed, He preserved Noah, the preacher of righteousness, when He brought the flood upon the world of the ungodly; and likewise Lot, who was oppressed by the wicked, when the Sodomites were seeking to abuse the angels who had been received as guests (Gen. 19), and who was daily admonished to emulate their wicked deeds, then tormented his own soul through soberness, and by abstaining from them, He rescued him: will He not much more deliver at this time those who are destined for destruction, just as He did the transgressing angels and those who were in the time of the flood, and furthermore the Sodomites? But you who dwell in the world along with them, will He not preserve you, just as He did Noah and Lot who then lived among the ungodly? No one doubts that He will indeed do so. For He knows how to rescue the godly from temptations and to keep the unrighteous under punishment for the day of judgment. Note, however, that when he previously presented the example of the wicked, he now ordains that which is about the righteous: by this, he also consoles the imitators of the righteous, who are considered superior to the impious. Therefore, Christ also gives the reward first to the just sheep who are on the right, and then to the goats who are on the left, punishments. (Matt. 25:34-41) Since delightful things are preferred over sad ones.
"God did not spare the angels who sinned." He attacks those who were first cut off and says: If the angels who were in honor with God because of the immortality of their substance, when they had shaken off the yoke, sinned, they did not obtain forgiveness: much less will God spare men who cling to their own creation if they have sinned,
Therefore, since a single response of speech was not sufficient to fulfill the proposed matter, it remained in another way in phrasing, and completed what was necessary through an interjection. But why he mixed examples of good with bad ones will be explained in a suitable place.
"But the eighth person," etc. As we have previously stated, it follows not only from what is evident in the discourse, but also from their understanding of what is proposed. For the response of the discourse is not one that usually follows such arrangements, but is a simple persuasive example, concerning those who are punished for their sins, and those who are honored for their righteousness: as if to say; The Lord knows how to punish sinners without sparing them, just as He did the angels who sinned, as well as those who were in the time of the flood, like the cities of Sodom and Gomorrah; again, to honor those who practice righteousness, such as Noah and Lot. And this is the arrangement: Having said that false teachers are to be punished for their blasphemies and their lustful lives, he adds examples.
For God did not spare the angels who sinned, nor the ancient world, nor did He spare the cities of Sodom and Gomorrah from destruction, but they are reduced to ashes, serving as a punishment for the ungodly. Again, God knows how to honor those who exercise justice, just as He did with Noah and Lot: and for the righteousness of each, it is narrated that both Noah and Lot were preserved from the destruction of the men who lived during their time because of their soberness and chastity. For they were not taken away from the impiety of those who were before the flood.
Lot also did not follow the carnality of those who lived in Sodom, but as if provoked daily by the sight of those who acted impolitely, he was stirred to the same boldness, yet he did not succumb in any way. For this means, "with seeing and hearing," (2 Peter 2:8) that he had many things that could provoke him to boldness, sight, hearing, conversation among the wicked; but he neither delivered the angels, his guests, in the appearance of men, to those who sought them because of their impudence, although he suffered violence from them in countless ways. For this is indicated by saying that he was oppressed. And as figure of speech, Peter adds: " The Lord knows how to rescue the godly," etc. (2 Peter 2:9) However, since he had not forewarned anything about the righteous, but only about the wicked and their punishment, he also scatters examples of the righteous in this place: first, indeed, because the history simultaneously mentions both the destruction of the wicked and the salvation of the righteous; then, moreover, from this comparison, he amplifies the malice of those who sinned, and makes the good works of those who conducted themselves excellently clear. Furthermore, Peter persuades the listeners to indeed hate the shamelessness of those, but to embrace the noble work of these for the sake of salvation. Hence, he also mentions in a figure of speech, both the pious and the impious, and salvation and punishment. Moreover, what he wants from this has already been stated, namely that he desires for them to hate the wickedness of those, but to emulate the salvation of these. "For the just is with sight and hearing." Although he had many things that inflamed, stimulated, and invited to shamelessness—eyes, ears, and conversation among the wicked—he was not, he says, led to the imitation of them.