Lot was saved from the raging fires that Hashem sent to destroy Sedom. Rashi brings down from Chazal that Lot was saved in the merit of his keeping his mouth shut when Sarah was taken by Pharaoh and Avraham said that Sarah was his sister. Lot could have spoken up then and told the guards that Sarah was really married to Avraham and this would have granted Lot much monetary reward and perhaps even Avraham’s entire wealth had Avraham been executed. Instead, Lot controlled his temptation and kept quiet. In this merit, Lot was saved from being killed along with his fellow city members in Sedom.
The question is that Lot certainly had other merits as well. When the three angels came disguised as men to the city of Sedom it was Lot who risked death by inviting them in and doing Hachnasas Orchim, hospitality. Why was it specifically that above mentioned merit that saved him?
Rabbi Yisrael Salanter (1810-1883) gives his most famous answer here. Hashem rewards a person according to his efforts expended and the harder it was for someone to do something, the greater reward the act receives. For Lot, who grew up in Avraham’s household, chessed and care for guests was a natural occurrence. He saw Avraham and Sarah host and care for guests and it became a habitual part of his essence. Thus, the act of Lot inviting in the angels is not impressive as it did not require any stretch on Lot’s part. On the other hand, Lot had a burning desire for wealth and was deeply greedy. The self-control that it required for him to keep his mouth shut in order not to turn in Avraham was the greatest internal act of strength that Lot had ever displayed. That act is what saved him from death for it carried the greatest merit.
When Hashem offered the Torah to the other nations each one of them questioned Hashem and wanted to know what laws the Torah entailed (See Sifri Vzos HaBracha). Hashem told Eisav’s descendents, “you may not kill.” They replied that it would be impossible for them to accept the Torah for that was their specialty “Yadayim Yidey Eisav.” To Yismael Hashem, “you cannot steal.” They couldn’t accept the Torah because that was their livelihood. To Amon and Moav Hashem said, “you may not commit adultery.” They rejected it stating that their entire existence stemmed from the adulterous relationship of Lot and his two daughters who bore them. Each nation rejected the Torah as a result of its conflict with their very essence.
This seems unfair, why did Hashem only preview to them their hardest challenge, would it not rather have been more appropriate for Hashem to have told them about the positive things in the Torah such as Shabbos, Mezuzah or Lulav? The answer is that Hashem was expressing to them the goal of Torah observance. Torah is meant to perfect man by taking his weakest point and turning himself over to the will of Hashem. Torah is meant to bring man to perfection through hard work. Torah inspired and changes a person at his or her core. The most worthwhile accomplishments in life are the ones that we worked hardest to achieve. Lot’s descendents of Amon and Moav did not learn a lesson from the grandfather regarding the value of internal work and effort. The Jewish people embraced the Torah and when Hashem asked them if they wanted the Torah, they did not ask any questions, rather, they proclaimed, “Naaseh V’Nishmah,” they were ready to put forth their full effort and to perfect themselves to the core with dedicated actions and commitment to truth.