Interesting commentary I found about this week's Torah's portion:
We’re told in Parshat Vayera that Sodom is a wicked and miserable place, and we know the inhabitants of Sodom were “very wicked sinners against the Lord.”1 But we’re left wondering what they could have done that that was so wicked that now God wants to destroy them.
For most Jewish thinkers, the evil of the men of Sodom had nothing to do with sex.2 Instead, the mainstream of Jewish tradition has understood the terrible evil of Sodom to be its residents’ lack of concern and even hatred for those in need. As the Talmud imagines things, the residents of the city were comparatively wealthy, as the valley of Sodom was the most fertile land in Israel.3 Knowing that those in need seek help from those who have resources, the Sodomites passed laws prohibiting any citizen from welcoming visitors, lest one poor person tell another that charity was to be found in Sodom and the city be flooded with poor people.4
Simply put, God destroyed Sodom and Gomorrah with fire and brimstone because they were more concerned with protecting their wealth than with protecting the needy...
http://www.ajws.org/uploaded_documents/Bereishit-Vayera%205766%20FINAL.pdf