What does Genesis 20:2 mean?

After moving to a new place, Gerar, Abraham repeats an old scheme he had used much earlier in his life. Genesis 12 reports that Abraham had moved his household into Egypt, forced out of Canaan by a famine in the land. At that time, he was afraid someone would notice his wife's great beauty and kill him to get her (Genesis 12:12). So, he asked Sarah to tell a half-lie for him: Say you are my sister. She was, in fact, his half-sister. They shared the same father, but different mothers (Genesis 20:12). Perhaps Abraham thought someone would ask his permission to marry her and, as her brother, he could simply refuse.

It didn't work. An Egyptian Pharaoh simply took her, added her to his harem, and paid Abraham great sums as her brother. Then, as He often will in these instances, God stepped in to resolve the situation. Here, God will eventually do the same.

This is a frustrating incident in the life of Abraham, who has recently seen many signs of God's great power and faithfulness. Even so, Abraham acts out of fear and faithlessness. Once again, the lie backfires. The king of Gerar, Abimelech, takes Sarah for a wife, believing her to be Abraham's sister.