Rashi explains that the fate of the people of that generation was sealed as a result of theft. The members of the dor hamabul, generation of the Flood, were guilty of many other and more egregious transgressions. Why did theft play such a critical role in their fate? Furthermore, it is a well-established maxim that Hashem does not exact punishment on a person’s body until He has exhausted all other avenues of punishment. We see that the individual who is guilty of behavior which brings on the onset of tzaraas, spiritual leprosy, first notices the plague on his house and his possessions before Hashem strikes him personally on his body. Hashem gives him various hints concerning his deficient behavior, various opportunities to repent and change his ways, thereby circumventing the tzaraas that affects his body. Why, then, did the dor hamabul not receive Hashem’s message enacted on their possessions prior to receiving the ultimate punishment?
The Maharam Schick, zl, explains that it is only when one obtains his possessions through appropriate means that they can save him, that they serve as a medium for delaying his personal punishment. If, however, his material belongings have found their way into his possession through illegal avenues, then they are not really his. That which is not his cannot protect him. Thus, if one steals, his possessions do not protect him, because they are not his. This is the meaning of the idea that the fate of the dor hamabul was sealed as a result of theft. Their possessions could not protect them, because they had been obtained illegally.
This is a powerful message to those who feel that they can “have their cake and eat it too.” One who obtains money through means that are less than honest loses the protective coating that his possessions could potentially avail him. Not only is he a thief, but he will pay dearly with his health and welfare for his corruption.
In an alternative exposition, the Tiferes Shlomo explains that ki malah ha’aretz chamas, “The earth had become filled with robbery,” was actually a middah k’neged middah, measure for measure, payback for the way the people of that generation were treating one another. He begins by asking how theft could have such a powerful condemning effect that the entire generation was wiped out as a result of this form of corruption. Animals steal from one another all of the time. So, these people had descended to the level of animals. Does this behavior mandate such severe punishment?
He quotes the Midrash that relates that Avraham Avinu met Shem ben Noach and asked him in what merit his family had been spared from the effects of the Flood. Shem replied that he did not know, other than the fact that they had devoted themselves for an entire year, day and night, to serving the needs of all the creatures on board the Ark. Perhaps, in this merit, Hashem had spared them.
As a result of their incredible compassion for the creatures in their charge, Hashem repaid them with exceedingly great compassion. The members of the dor hamabul, however, were thieves who did not care for one another. Another person’s feelings meant nothing to them. If they could have exhibited compassion to others, Hashem would have had compassion on them and not sent the waters of the Flood. When the members of a generation are steeped in chamas, theft, when they show no feeling towards others, then they deserve none for themselves. Hashem has rachmanus, compassion, for those who manifest compassion towards others.