I have another idea: The angels went on to judge Sdom and see if Avraham was correct. They were ready and willing to save Sdom. What happened? Sdom in its actions proved that it deserved to be destroyed.
This is clear from the plain reading of the text. The angels went to Lot and ate a meal by him. They didn't mention anything about the destruction until after the entire city had gathered on Lot's doorstep demanding he bring out the visitors.
Specifically the language of this passuk is curious:
טֶרֶם, יִשְׁכָּבוּ, וְאַנְשֵׁי הָעִיר אַנְשֵׁי סְדֹם נָסַבּוּ עַל-הַבַּיִת, מִנַּעַר וְעַד-זָקֵן: כָּל-הָעָם, מִקָּצֶה.
The last word מקצה is unusual. It means from the end. But there's a deeper meaning in this word. קצה has the gematria 195. If you take all the numbers mentioned in Avraham and HaShem's discussion, 50 + 45 + 40 + 30 + 20 + 10 = 195. The same number as the gematria of קצה. Meaning that every person that Avraham tried to argue might be considered a tzaddik in order that Sdom might be saved came out that night and proved his own evil nature. HaShem then, fulfilling His deal with Avraham, found Sdom wanting. At which point the angels intercede, save Lot, and destroy Sdom.
The last word מקצה is unusual. It means from the end. But there's a deeper meaning in this word. קצה has the gematria 195. If you take all the numbers mentioned in Avraham and HaShem's discussion, 50 + 45 + 40 + 30 + 20 + 10 = 195. The same number as the gematria of קצה. Meaning that every person that Avraham tried to argue might be considered a tzaddik in order that Sdom might be saved came out that night and proved his own evil nature. HaShem then, fulfilling His deal with Avraham, found Sdom wanting. At which point the angels intercede, save Lot, and destroy Sdom.
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