In the third place, by the use of various figures, Paul contrasts the former bondage with the present freedom. Gal. 3:23 to 4:7. The life under the law was a period of restraint like that of childhood, preliminary to faith in Christ. The law was intended to produce the consciousness of sin, in order that the resultant hopelessness might lead men to accept the Saviour. Vs. 23-25. But now all Christians alike, both Jews and Gentiles, are sons of God in Christ, and therefore heirs of the promise made to Abraham. Vs. 26-29. Being sons of God, with all the glorious freedom of sonship, with the Spirit crying, "Abba, Father," in the heart, how can we think of returning to the miserable bondage of an external and legalistic religion? Gal. 4:1-11.
In the fourth place, Paul turns away from argument to make a personal appeal. Vs. 12-20. What has become of your devotion to me? Surely I have not become your enemy just because I tell you the truth. The Judaizers are estranging you from me. Listen to me, my spiritual children, even though I can speak to you only through the cold medium of a letter!
In the fifth place, Paul, in his perplexity, bethinks himself of one more argument. It is an argument that would appeal especially to those who were impressed by the Judaizers' method of using the Old Testament, but it also has permanent validity. The fundamental principle, says Paul, for which I am arguing, the principle of grace, can be illustrated from the story of Ishmael and Isaac. Ishmael had every prospect of being the heir of Abraham. It seemed impossible for the aged Abraham to have another son. Nature was on Ishmael's side. But nature was overruled. So it is to-day. As far as nature is concerned, the Jews are the heirs of Abraham--they have all the outward marks of sonship. But God has willed otherwise. He has chosen to give the inheritance to the heirs according to promise. The principle of the divine choice, operative on a small scale in the acceptance of Isaac, is operative now on a large scale in the acceptance of the Gentile church.
Finally, Paul concludes the central section of the epistle by emphasizing the gravity of the crisis. Gal. 5:1-12. Do not be deceived. Circumcision as the Judaizers advocate it is no innocent thing; it means the acceptance of a law religion. You must choose either the law or grace; you cannot have both.