why the malach sent to destroy Sdom visited Avraham first

After posting earlier in the week about "Lot yosehiv b'Sdom," I guess the logical place to start on the new parsha would be the description of Avraham, "v'hu yosheiv pesach ha'ohel."  Avraham experienced post-milah a tremendous revelation of G-d's presence, and nonetheless, Avraham remained "yosheiv," present tense, in the doorway, at the threshold, feeling not yet there, like he had not yet entered and arrived at where he wants to be (Sefas Emes).  That's how we all should feel, otherwise we would stop growing.

Chazal tell us that the three visitors who came to Avraham were in reality three malachim, one of whom came to heal Avraham, one of whom came to tell Sarah that she would have a child, and one of whom came to destroy Sdom. Why did this last malach need to visit Avraham’s home? Couldn’t he have gone directly to Sdom?  (See Gur Aryeh)

One of the strategies used by oppressors is to dehumanize their victims and enemies so that it becomes easier to treat them harshly.  The Torah takes the opposite approach.  The Ne’os Desheh of Ishbitz explains that before administering justice, the malach of din needed to first see the potential for greatness in mankind -- the gemilus chassadim Avraham demonstrated and the heights simple flesh and blood can rise to.  At first, when the malachim arrived they were “nitzavim alav,” standing above, i.e. on a higher madreiga, than where they thought even Avraham could be holding.  By the time the food was served, “v’hu omeid aleihem,” he stood above them.  When they left, the Torah tells us that Avraham escorted his guests, “v’hu holeich imam."   Something of Avraham’s chessed was carried with those angels even as they continued on their way to fulfill their mission of destruction.  Avraham's efforts could not help Sdom, but the payback would come years later when Bnei Yisrael themselves would be deserving of punishment but would be spared.  The midas ha'din was tempered by having seen the greatness of Avraham's home.  (I'm not sure what I wrote fits what the Ishbitzer says exactly, so blame me if you don't like it, and see Sefas Emes in a few places on "ha'michaseh ani mei'Avraham" who says something similar).

The malachim finally get to Sdom in time for a Pesach seder with Lot.  What's going on here with Lot baking matzah to serve them?  I think the answer is that this is Lot's yetzi'as Mitzrayim.  This is the night where even though "halalu ovdei avodah zarah v'halalu ovdei avodah zarah," even though Lot was not so different than the people of Sdom (after all, he chose to live there), and might not even deserve to be saved on his own merits, he would get pulled out of the fire.  Just as Bnei Yisrael could not tarry when they left Egypt, the malachim tell Lot not to tarry -- to just run. 

"Va'tabeit ishto mei'acharav..."  On the way, Lot's wife looked back.  Shouldn't it say "mei'achareha," in the feminine?   When Moshe Rabeinu asked Hashem to reveal Himself, meaning, to explain the mystery of tzadik v'ra lo v'rasha v'tov lo, Hashem answered, "v'ra'isa es achorai u'panay lo yeira'u," you can see my back but not my face.  We can only understand in hindsight, from a great distance away in time.  We cannot understand things so clearly as they unfold before us.  Lot's wife looked back at Sdom and struggled at that moment to understand the "mei'acharav," the back of Hashem, the hindsight view, the explanation for Divine justice.  That was a privilege that she did not deserve to enjoy. (see Alshich)