What does Galatians 3:17 mean?
Paul is building the legal case for why those who are in Christ by faith, even non-Jewish people (Gentiles), become descendants of Abraham and receive the blessings promised to him. In the previous verse, Paul said that even a human covenant, or "will," cannot be changed once it has been ratified. When that kind of document was officially approved by all parties and legally filed, it was irrevocable.Now Paul clarifies the point of his illustration. God made a covenant with Abraham. That covenant was a one-way promise by God to bless Abraham and his offspring in specific ways. The Judaizers were apparently telling people that the law replaced God's covenant promises to Abraham (Galatians 2:4). Paul soundly rejects that idea. Although the law was instituted 430 years later, under Moses, it did not void out God's previous promises to Abraham. Those remain in effect, because God's covenant cannot be changed.
In the last verse, Paul made a point of indicating that this promise was given to Abraham's "singular" offspring, not a "plural" group or collection of many. Judaism had always believed that the promises given to Abraham would one day be fulfilled in a single person—a Messiah.
Jesus, as Abraham's ultimate offspring, received those covenant promises made to Abraham. That's why all who trust in Christ's death for their sin—placing their own lives "in Christ"—also receive the blessings promised to Abraham's offspring. We receive whatever Jesus is entitled to because we have been given credit for His sinless life, and He has taken the penalty for our sinfulness.
Galatians 3:15–22 begins with Paul making a legal argument about God's covenant with Abraham. This arrangement remained in place even during the later covenant of the law of Moses. Paul follows this by describing what the point of the law really is. It was given both to show what is sinful, and to show how sinful we are. By the law, we learn that we are not able to keep to God's standard and must be saved in another way. That other way is through faith in Christ. Once He arrived, this salvation was available to all people, including non-Jewish Gentiles.
Paul indicates the Galatian Christians are foolish for believing they need to follow the law of Moses to be right with God. He offers three specific arguments to support this. First, they received God's Spirit in a powerful way after believing in Jesus, but before doing any works of the law. Second, Scripture itself shows God's blessing coming by faith, and His curse coming by the law. Christ paid the price of that curse on the cross. Third, God's covenant with Abraham is like a legal document, and it cannot be revoked.