Having thus vindicated his apostolic authority against the false teachers in Galatia, he proceeds, in the second part of the epistle, to unfold the great argument for justification by faith in Christ. The Galatians have received the Holy Spirit, with the accompanying miraculous gifts, not by the works of the law, but by faith in Christ (chap. 3:1-5); Abraham was justified by faith, as an example for all future ages (verses 6-9,18); the law cannot bring justification to sinners, but only condemnation (verses 10-12); from this condemnation Christ delivers us, and makes us through faith the children of Abraham, and heirs to all the promises which God made to him (verses 13, 14); the Abrahamic covenant, conditioned on faith alone, is older than the Mosaic law and cannot be disannulled by it (verses 15-17); the true office of the law was to prepare men for the coming of Christ, in whom all distinction between Jew and Gentile is abolished (verses 19-29); before Christ the people of God were like a child that has not yet received the inheritance, but is kept under tutors and governors, but through Christ they are like the same child arrived at full age, and put in possession of the inheritance (chap. 4:1-7). The apostle adds (chaps. 4:8-5:12) various arguments and illustrations, with pointed allusions to the false teachers who were subverting the simplicity of their faith in Christ; and he solemnly warns the Galatian Christians that by receiving circumcision they bind themselves to do the whole law—the whole law as the ground of their justification. They have left Christ, and thus fallen away from grace—forsaken a system of grace for one of works, so that “Christ is become of no effect” to them. Chap. 5:3, 4.
The third part (chaps. 5:13-6:18) is of a practical character. The apostle affectionately exhorts the Galatians to use their Christian liberty in a worthy manner, mortifying fleshly lusts, restoring fallen brethren in meekness, bearing one another’s burdens, and being diligent in every good work. In bringing the epistle to a close he contrasts the vain-glory and hypocrisy of these Judaizing false teachers with his steadfast purpose to glory only in the cross of Christ, in whom “neither circumcision availeth any thing, nor uncircumcision, but a new creature.”