Christ, by being "born under the law" (Gal. 4:4), personally fulfilled all of the law's demands as our convenant Mediator or Surety. This is how Christ is "our righteousness": his righteous, perfect keeping of the law in every particular is imputed to me as a fee gift (Rom. 5:17). Paul does not develop this point in our Galatians 5:1-6 passage, but he does express it when he says: "For through the Spirit, by faith, we ourselves eagerly wait for the hope of righteousness" (Gal. 5:5). I believe this principle of substitutionary mediation is expressed even more strongly--if succinctly--when Paul shows our complete identity with Christ in his death and in his life earlier in Galatians:
- For through the law I died to the law, so that I might live to God. I have been crucified with Christ. It is no longer I who live, but Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me. I do not nullify the grace of God, for if justification were through the law, then Christ died for no purpose. (Gal. 2:19-21)
Paul makes absolutely clear in the Galatians 5 passage that the two ways of righteousness are mutually exclusive: one either appropriates the gift of our Mediator's righteousness for which we hope and eagerly await through the Holy Spirit by faith (v.5; cf. Rom. 5:17; 2 Cor. 5:21) or one attempts to acquire that standing derived from the "works done by us in righteousness" (Titus 3:5). The latter is what the law of Moses commands: perfect performance by the individual, and there can be no admixture of circumcision and Christ (Gal. 3:3). Ironically, Paul says in Romans 7:6 that we in Christ have been severed from the law, but he says in Galatians 5:4 that those who come under the law have been "severed from Christ".
Furthermore, verse 4 unequivocally shows that there is no "gracious" fulfillment of the law which God accepts as a substitute for perfect and entire performance of its commands by the obligated person (v. 3). Paul says that all who would attempt to be justified by law have necessarily fallen from grace, since "grace" in this use is tied to the appropriation of the benefits of Christ's substitutionary mediation through faith and received as a gift (e.g., Eph. 2:8). The law here is tied to personal obligation without mediation; hence it is not "gracious" in this sense. This is what Paul had already communicated in brief in Galatians 2:21 where he links divine grace only to Christ's substitutionary death whereas justification through personal law-keeping is antithetical to and a vitiation of grace. [The Law Is Not Of Faith: Galatians 5:1-6 and Personal Obligation, pp. 276-277]