Lot's separation

We learned in class this week that when Avram, Sarai, and Lot went down to Mitzraim, they did not come back empty- handed. They had lots of cattle, money, slaves- you name it. Lot became corrupted with this wealth, but Avraham did not. They started arguing over this, but Avram has no desire to fight with Lot. They therefore split up and Lot went to Sodom, which he describes as "Kigan Hashem Kieretz MItzraim." This proves the fact that Lot has become corrupted, since he was comparing MItzraim, which was evil and corrupt, to the garden of Hashem! As a result of this, G-d must reassure Avraham that His promises will come true and that there is no reason to worry. This may be because Avram thought that since he was 75, the promise of descendants might have been fulfilled through Lot, but since he had gone astray, it wouldn't be fulfilled. G-d tells him that this is not the case; he will have children and the promise will be fulfilled through him. He then adds that all the land will belong to Avram and his descendants, not Lot. Avram then builds an altar to G-d, showing his renewed faith in G-d's covenant.