“But he who was of the bondwoman was born according to the flesh, and he of the freewoman through promise” (Galatians 4:23).
In the context of Galatians 4:23, the “bondwoman” of this passage referred to a woman named Hagar. Hagar was an Egyptian woman who served as the maidservant of Sarah, the wife of the Biblical patriarch Abraham. At Sarah’s suggestion, Abraham married Hagar and their relationship produced a son named Ishmael (Genesis 16:15).
The “freewoman” of this passage is a reference to Sarah and Genesis 17:15-16 provides us with the following information regarding her…
“Then God said to Abraham, ‘As for Sarai your wife, you shall not call her name Sarai, but Sarah shall be her name. And I will bless her and also give you a son by her; then I will bless her, and she shall be a mother of nations; kings of peoples shall be from her.'”
The book of Genesis goes on to tell us that Sarah later became pregnant and had a son just as God said she would. Abraham named his newborn son Isaac as God commanded and he represented the son who was born in fulfillment of God’s promise as mentioned here in Galatians 4:23. This background information is helpful in understanding the point behind this verse.
If we could paraphrase the idea behind this passage, we might do so in the following manner: “The legalists who are attempting to convince you to follow the Old Testament law claim that Abraham is their spiritual father. But the critical question is this: ‘who is their spiritual mother?’ Is it Hagar, the bondwoman who married and bore a son as a result of a human-oriented plan? Or is it Sarah, the freewoman whose son was born according to God’s promise?”
You see. Abraham’s relationship with Hagar personified the attempt to find acceptance with God through human effort. Abraham’s relationship with Sarah illustrated the path to acceptance with God through Christ who was born according to God’s promise and plan. One Biblical scholar expands on this concept with the following observations…
“Ishmael, the son of Abraham and Hagar, was born after Abraham and Sarah despaired of having the son God had promised. His birth was ‘according to the flesh’ because Hagar was fertile and of childbearing age when Sarah gave her to Abraham. Thus, Ishmael’s conception, though unusual in view of Abraham’s age, resulted from natural reproductive capacities.
Isaac, on the other hand, was born to Sarah by a miracle long after her childbearing years had ended (Gen. 11:30; 17:17; Rom. 4:18–21). God showed that none of His promises are empty (Gen. 18:14; Luke 1:37).” (1)
(1) Sproul, R. C. (Ed.). (2015). The Reformation Study Bible: English Standard Version (2015 Edition) (p. 2081). Orlando, FL: Reformation Trust.