Gálatas 3:7-9

"In this verse [Galatians 3:7] Paul extended his argument from Abraham to his posterity and raised for the first time the question that would dominate the remainder of Galatians 3, 4 : Who are the true children of Abraham? This train of thought will find a conclusion in the allegory of the two mothers, Sarah and Hagar, and their two sons, Isaac and Ishmael (Galatians 4:21-31)." [Note: George, p. 223.]

The spiritual sons of Abraham, Paul contended, were not his physical descendants but those who believed God whether they were Jews or Gentiles. He expounded Genesis 12:3 c and Genesis 22:18 a (in the LXX) to prove his point. We should understand this promise to include salvation. Paul clarified that this is what God intended. However it is only those who trust God who enter into God’s blessings for believers. Paul was not a universalist; he did not believe everyone will eventually go to heaven. Personal appropriation of God’s gift is necessary for salvation.

The Judaizers were evidently teaching the Galatians that to become Abraham’s children by adoption they had to receive circumcision. This was necessary for pagan proselytes to Judaism. They may have said that God had declared the Galatian Christians righteous by faith while uncircumcised like Abraham. Nevertheless now they needed to undergo circumcision as Abraham did. Circumcision would be a seal of their justification as it had been for Abraham. Circumcision would make them true sons of Abraham.

Paul argued that it was not circumcision that made a person a son of Abraham but faith. He treated circumcision as a part of the Law because, even though God instituted it many generations before He gave the Law, He reaffirmed it and incorporated it into the Law (Leviticus 12:3).

"What endeared Abraham to many Jewish thinkers were his virtues and his deeds. They understood him to have kept the law before it was written." [Note: Morris, p. 98.]