Chapter three begins the second of three sections with a question of accusation against Paul’s readers. Based on their movement toward away from faith toward works, Paul believed that they had been put under a spell of sorts. Galatians 3:1-5 are a figurative snapping of Paul’s fingers or shaking them awake from a trance. Had they so quickly (Galatians 1:6) forgotten how they were saved through faith that they were now requiring circumcision for new converts?
Using his favorite example (see also Romans 4), Paul pointed them to Genesis 15:6, where Abraham – the great father of the faith – simply believed, centuries before the Law was given (Galatians 3:6-14). At the same time Paul introduced Abraham’s spiritual family, consisting of those, and only those, who simply believe like he did, including Gentiles, as promised in the Abrahamic Covenant (Genesis 12:3). Paul also pointed out that one cannot obey only parts of the Law in order to be declared righteous. In fact, when one places himself under any part of the Law, he places himself under the entire Law and is subject to every part. Yet even that cannot provide salvation, because the Law could never do that. This is why Christ had to die, becoming a curse under the Law in order to free people from the Law and receive the promised Spirit.
In Galatians 3:15-22 he used classical Greek logic to clearly show the difference between the physical promises (plural) that were made to Abraham and his descendants and the spiritual promise (singular) that was made to Abraham and all who believe. Because the Law came after God made these promises, it could not invalidate the promises. Instead, it actually was intended to protect the Israelite people from defecting from God so that they could one day receive the promised Spirit through faith in Jesus. Under the Law, an inheritance could not be received by a Gentile, a slave, or a woman. In Christ, however, all people can receive the Spirit through faith, whether Jew or Greek, slave or free, male or female (Galatians 3:28). No believer is left out of the inheritance, because we “are all sons of God through faith” (Galatians 3:26). Those who attempt to use this to eliminate functional roles in the home or church (female elders, feminist theology, etc.) completely miss the context and are practicing eisegesis for their own purposes.