Noach’s generation committed three Aveirot. They practiced idolatry, engaged in sexual immortality, and stole. Interestingly, Rashi, commenting on (Bereishit 6:13) “Keitz Kol Basar Ba Lefanei Ki Male’ah HaAretz Chamas MiPeneihem VeHinnini Mashchitam Et HaAretz,” “The end of man has come because violence has become rampant and behold I will destroy the earth,” notes that the straw that broke the camel’s back was stealing.
This seems very puzzling. Why would stealing be the reason to destroy the world and not idolatry and sexual immortality? After all, idolatry and sexual immortality are two of the three Mitzvot for which one must be willing to give his life rather than commit! If the reason would be because stealing is Bein Adam LaChaveiro, between man and man, sexual immortality can also be Bein Adam LaChaveiro, such as in a case of adultery.
The Griz (Shemos 22:21-22) answers by citing a Pasuk in Parshat Mishpatim: “Kol Almanah VeYatom Lo TeAnun Im Anei Te’anah Oto Ki Im Tzaok Yitzak Elei Shamo’a Eshma Tzaakato,” “Don’t oppress any orphan or widow; if you do mistreat him, when he cries out to Me, I will indeed hear his cry.” Now, surely Hashem will help the downtrodden whether they cry out or not. But if the pain is such that they cry out, then He will take up their cause more speedily. When it comes to stealing, the oppressed cry out. This is not the case regarding idolatry and sexual immortality because these sins are committed with the consent of all parties involved. Therefore, Hashem brought the Mabul only because of stealing .
Rav Elyakim Getzil Livyatan offers a different explanation. Chazal teach us (Rosh HaShanah 17b, see Rashi ibid. s.v. ULeVasof) that when HaKadosh Baruch Hu created the world, He at first wanted the world to be run solely in accordance with Midat HaDin. However, once He realized that it wouldn’t work, Hashem added Midat HaRachamim. The way Midat HaRachamim works is that Hashem lessens punishment for the sin. However, when it comes to stealing there can’t be any Rachamim on the behalf of the perpetrator because the Rachamim is required for the victim!
This can be explained with a Mashal. There was once an evil man who was beating up a poor, defenseless old man. An angry man who often hits people witnessed this happening but wasn’t bothered by it and just passed on. Then came a delicate man who was always concerned for everybody’s feelings. The man was overcome with anger and beat up the evil man, thereby saving the old man. When asked how he could strike the evil man, the delicate man replied that he couldn’t just stand idly by when the poor old man was being beaten up. The mercy that he felt for the old man overcame his natural aversion to hurting others
This is the essence of the Midat HaRachamim. Hashem “can’t” express mercy for the perpetrator when He is expressing mercy for the victim. This is why stealing was the last straw, because Midat HaRachamim could not defend the Dor HaMabul.
As Jews we unfortunately know very well the dangers of standing idly by our brethren are being harmed. We must always look out for our fellow Jews whenever they are in need. If someone feels they should be merciful and not take action, in reality he just being cruel.