"And the two angels came to Sodom in the evening and Lot was sitting at the gate of Sodom." (From this week's Torah portion, Vayerah, Genesis 19:1)
Hold on a minute! Didn't Lot learn anything from his previous misadventure? Just in last week's Torah portion, Abraham endangered himself and his entire family in a World War to save Lot from captivity after he made his bad decision to move to Sodom. After Abraham redeems him, Lot disregards everything that transpired and goes right back to Sin City as if nothing had happened, at all.
In order to understand this psychosis, all we have to do look at all the Israelis applying for citizenship in the countries that brought us Auschwitz. Lot probably told himself that his capture at the hands of the kings was nothing more than a historic accident. If the four kings had not warred with the five kings, it would never have happened. The Israelis lining up outside the Polish and German embassies share the same line of thinking: If there hadn't been a war, the Holocaust would never have happened. Wars, however, are not the reason for holocausts; they are simply the opportunity to perpetrate them. Even after the war, the Polish continued to slaughter the Jews who dared return home from the death camps.
The question is not why Lot returned to Sodom, but why Abraham endangered his entire historic mission and set out on an illogical war to save him. After all, he had enough money to redeem him from captivity. In no place in the Torah does G-d command Abraham to fight this war. Did Abraham exercise poor judgment? Why put his years of building and effort on the line for his rebellious nephew who knowingly went to live in Sin City?
The answer is that Abraham did not go to war to save only Lot; he went to war to save his mission. Lot's capture placed his entire destiny on the scales. Everybody knew that Lot was Abraham's nephew, and they waited to see how Abraham would react. Abraham understood that if he would not be willing to endanger himself and fight for his relatives, he would no longer be respected. Worse than that, he would lose the legitimacy for his very existence. From here on in, he would be dependant on the kindness of others.
This war is listed by our Sages as one of Abrahams' ten trials. Abraham had to overcome his personal considerations and respond to the affront to his sovereignty like a free nation - making him worthy to establish the Nation of Israel.
After Abraham successfully traverses this trial and wins the war against the kings of the north, G-d makes a covenant (the Covenant of Pieces) with him and promises him the Land of Israel. Sounds strange? G-d "sides with" the winner? Not at all. G-d chooses the man who is willing to fight for his destiny, and not just for his existence.