The moral implications of Avraham’s descent to Egypt and Sarah’s being taken by Paroh trouble all. Rashi says that Avraham’s journey was a test passed - he did not complain about being exiled from Eretz Yisrael soon after arriving. Rashi does not comment on Sarah’s being taken after Avraham said she was his sister. The P’nei Yehoshua (Ketubot 61a) rejects the face value understanding of the comment that Avraham received presents for his acquiescence. The Ramban takes Avraham to task for his role. Fear should not have caused him to leave Eretz Yisrael or allow Sarah to be compromised; Hashem can save in any situation. The Ramban says that Avraham’s behavior brought on his descendants’ painful exile in Egypt.
We will try to chart a course between the extreme positions above. We have explained that the patriarchs were not just heads of a family but were "political" heads of a large constituency of many thousands. Avraham’s followers converted to belief in monotheism. He negotiated and interacted on high levels with local kings and superpowers and led his followers to victory in battle over major armies.
Throughout Tanach, the following assumption appears in the background of stories. Marriage between monarchal families was used to forge ties between kingdoms. The more powerful side often took the daughter of the weaker king. This is behind Shlomo’s marrying of Paroh’s daughter and the midrash that Avraham’s servant/concubine, Hagar, was Paroh’s daughter. (See also Daniel 11:6.)
Avraham referred to Sarah as achoti, which usually means a biological sister. However, we find that an achot can refer to a more intimate male-female relationship (see Shir Hashirim 4:10). Some scholars have claimed that Sarah’s transition from Avraham’s wife to his achot indicates a divorce of sorts. (The Mishneh Halachot (VI, 263) independently cites from the Gaon of Ostravska that Avraham had indeed formally divorced Sarah so as not to cause her and Paroh to violate adultery.)
Avraham was forced by famine to bring his group to Egypt and to capitulate to Paroh regarding the terms of their stay. Paroh demanded to be able to take one of the women in his entourage as a wife, and as Avraham feared that he might take Sarah, he formally divorced her and made her an achot. That is why the difficult midrash (Tanchuma, Bechukotai 3) said that she was elevated in status when she was taken by Paroh to be a wife. At the end, miracles forced Paroh to admit that Avraham was the more prominent leader, as the teacher of monotheism, and gave over his daughter to be a servant in his household (Bereishit Rabba 45).
Let us pray that the world will understand that the real dominion is Hashem’s and all will want to attach themselves to His Kingdom.