Galatians 3:15—4:7 provides a carefully reasoned argument by Paul in defense of his proclamation of the gospel to the Gentiles. Buttressing his arguments with passages from the Old Testament, Paul set forth a new understanding of how God has worked since the time of Abraham to bring all kinds of people into intimate relationship with God. That relationship flows through Christ Jesus and reaches its zenith when the Spirit compels us to embrace God as Abba Father.
1. Paul’s argument begins with the premise that a covenant, a testament or a will (think here of a “last will and testament”) once established cannot be altered or set aside (3:15)
2. God’s covenant was established with “Abraham and his seed” and was based on a promise that the covenant would be everlasting, beginning with Isaac and his “seed” (3:16a; cf. Gen. 17:19b).
3. Since the Hebrew word “seed” is singular in Genesis 17:19b, Paul concluded that it refers to one person. That person is Christ (3:16b).
4. This covenant with Abraham was made by God 430 years before the law was given to Moses (3:17a).
5. The giving of the law to Moses did not set aside or do away with the earlier covenant and its promise (3:17b).
6. The “inheritance” that belongs to Abraham’s seed is based on the covenantal promise and not on the law (3:18a).
7. This inheritance is a gift of grace and is not in any way the result of human accomplishments like obeying the law (3:18b).
8. The purpose of the law was to address human sinfulness until Abraham’s seed (Christ) had come and the covenantal promise could be fulfilled (3:19; cf. Romans 5:20).
9. The law was given through a mediator (Moses, cf. Exod. 20:19) and was put into effect by angels (cf. Acts 7:53; Deut. 33:2); but the promise to Abraham did not involve a mediator (who must represent both parties in a covenant) and was made directly by God (3:19c-20).
10. The whole world is a prisoner of sin, and this is evidence that the law cannot save (make one alive) or impart righteousness (3:21-22a).
11. The law locked up God’s people as prisoners and “supervised” them until faith was revealed (3:23-25).
12. By grace Abraham’s promise is given to those who have faith in Jesus Christ (3:22b, 23-25).
13. All who believe in Jesus Christ and belong to him become Abraham’s seed and inherit Abraham’s promise, whether they are Jew or Greek, slave or free, male or female (3:26-29).
14. A child under the law, though a heir of the promise, is no different from a slave under the authority of the law (4:1-3).
15. God sent the Son, born of a woman and born under the law, to redeem those under the law (4:4-5a).
16. Christ’s redemption provides an opportunity for all to received the full rights of inheritance (4:5b).
17. God sends the Spirit of the Son into the hearts of those who claim the inheritance so that they in the Spirit can call out, “Abba, Father” (4:6).
18. This confession transforms slaves into sons and thus into heirs of the covenant’s promise (4:7).
The purpose of this detailed argument was to set believers free from the obligations of the law that the Judaizers were trying to impose on the Gentiles in Galatia. The redemption offered by grace through Christ countered the Pharisaic tendency to focus on earning merit through obedience to every jot and tittle of the law. Paul later stated that “Christ has set us free” (5:1). The focus on the law was a burdensome “yoke of slavery” (5:2). Paul, however, also cautioned against the “freedom to indulge the sinful nature” (5:13) and called for believers to live by the Spirit and not by the desires of their sinful natures (5:16). “The fruit of the Spirit” (5:22) would guide them to “do good to all people” (6:10).