“Nevertheless what does the Scripture say? ‘Cast out the bondwoman and her son, for the son of the bondwoman shall not be heir with the son of the freewoman.’ So then, brethren, we are not children of the bondwoman but of the free” (Galatians 4:30-31).
Galatians 4:30 references a historical event from the book of Genesis to serve as an example for those who were seeking to find acceptance with God through the works of the Law. That account describes an incident that took place as the great Old Testament patriarch Abraham celebrated the fact that his young son Isaac had graduated from drinking milk to eating solid food. Abraham decided to hold a feast to commemorate the occasion but one guest wasn’t in the mood to celebrate…
“The child grew and was weaned, and on the day Isaac was weaned Abraham held a great feast. But Sarah saw that the son whom Hagar the Egyptian had borne to Abraham was mocking” (Genesis 21:9-10 NIV).
The son of “Hagar the Egyptian” was Ishmael who was probably around 16 years old at that time. While we don’t know what Ishmael was mocking, we do know that Isaac’s mother Sarah was very displeased…
“and she said to Abraham, ‘Get rid of that slave woman and her son, for that woman’s son will never share in the inheritance with my son Isaac'” (Genesis 21:10 NIV).
The fact that Sarah used an emotionally charged term like “that slave woman” tells us that she took Ishmael’s conduct as a personal affront. You see, Hagar had acted with an attitude of contempt and disrespect for Sarah when she was pregnant with Ishmael. Now Ishmael was repeating that same type of behavior with Isaac. So from Sarah’s perspective, the mother and the son each deserved to be dismissed.
Paul the Apostle used this incident to illustrate the challenge posed by those who advocated a relationship with God based on human effort. The legalists who sought to approach God on the basis of their good works could not co-exist peaceably with idea of salvation by grace through faith. One commentator brings closure to this portion of Scripture and prepares us for our look at the final chapters of this great epistle…,
“This verse brings to a climax the argument that believers are not a community or nation in bondage to legal statutes, but members of the community of believers whose relation to God is that of sons, and who do not have the spirit of bondage but the Spirit of sonship. It also serves as the basis upon which Paul builds the practical instruction which follows in chapters five and six.” (1)
(1) Kenneth S. Wuest, Word Studies in the Greek New Testament (Galatians 4:31) Copyright © 1942-55 by Wm. B. Eerdmans Publishing Co.