blownaway,
Account involving Lot and Abraham was obviously fabricated for grander purposes—for introducing Exodus and Ransom sacrifice of Jesus. An unbiased reading would show that writer of Genesis is struggling to create details, and in his desperation repeating the details already written in small scale into large scale later:
a) Abraham is brought out of Chaldeans to “take possession of land” (Genesis 15:7)—a small scale incident as a foreshadow of Israel being brought out of Egypt to “take possession of land”—a large scale event.
b) When God informed of His intention of destroying the wicked inhabitants of Sodom and Gomorrah Abraham made extensive questioning, cross-questioning and bargaining with God till he gets satisfied. (Genesis 18:16-33) However, when God informed of His intention of murdering Abraham’s own only-begotten, innocent son, he simply obeys without any questionings [which he should naturally have done more intensely than he did in the case of unrelated wicked people where Lot was living]. To provide a basis for Abraham’s story, they had to invent Lot, and destruction of Sodom and Gomorrah—a story with no purpose because Lot’s daughters finally had to ‘get their father to drink wine so that they could lie down with him to have children from him’ (Genesis 19:30-36), children (Moab and Ben-Ammi) who became the ancestors of two nations Moabites and Ammonites that became enemies of Israel.
To produce one incomprehensible story of God offering His son to be murdered as sacrifice for the sins of the world, see how many incomprehensible stories that must precede it!