Ch. 19 starts out by saying that the two angels went on to visit Lot in Sodom. This reaffirms the idea that of the "three men" who appeared to Abraham, one of them was not an angel and most likely the Son of God.
The next bit of the story is simply disgusting and difficult to read. Every man in the city surrounds Lot's house and demands that he send out the two men so that they may gang rape them. This is where the modern day term "sodomy" comes from. As if this wasn't disgusting enough, Lot behaves in a cowardly/shameful way by offering up his two daughters to be subjected to this act of rape instead. God intervenes in this situation and decided to destroy this wicked city.
After escaping Sodom, Lot and his two daughters are living in a cave. His daughters decide to get him drunk and sleep with their father so they will have children. Again, disgusting and shameful behavior.
Ch. 20 has us back with Abraham and Sarah, with Abraham once again behaving in a cowardly way by pretending to be Sarah's brother and allowing a king to pursue her.
When most people read these two chapters they tend to focus on the homosexual sins mentioned here. But as I was reading it, the behavior that was the most disgusting to me was the overall low view and shameful treatment of women during this time. Wives and daughters were treated as property--as assets to be used for whatever one needed them for. This was never God's plan! It's tempting to read these Biblical stories and assume that God must have been okay with it because it's in the Bible. Not so. It was just as shameful and sinful then as it would be now.