Once More on Bondage versus Liberty
In our present verses, the two sons of Abraham are in view. "Abraham had two sons." Although these boys (Ishmael and Isaac) were actual historical characters, they represent a spiritual allegory: "which…are symbolic." These two sons provide a vivid historical illustration of law and grace. "For these are the two covenants."
Ishmael, the first of Abraham's sons, pictures a life of self-sufficiency under the law: "the one from Mount Sinai." Such an approach to life produces spiritual bondage: "which gives birth to bondage." The citizens of earthly Jerusalem are also given as an example: "and corresponds to Jerusalem which now is, and is in bondage with her children." When Paul wrote Galatians, the Roman empire held the city of Jerusalem in oppressive bondage. Abraham and Sarah trusted in their human ingenuity, using Hagar to bear their child. Thus, Ishmael was born, a child of fleshly bondage.
This is what our lives are like when we try to produce a Christian life by our own sufficiency. We are placing ourselves under the law (performance-based living). This is a path of spiritual bondage. We can only bring forth "fleshly Ishmaels."
Isaac, the second of Abraham's sons, is a portrait of living under grace. God's sufficiency is now the source. Isaac was born by God's faithfulness in fulfilling His promises. Trusting in God's faithfulness produces spiritual freedom. Heavenly Jerusalem is the example here. "The Jerusalem above is free, which is the mother of us all." We who follow Christ have been born again with new life from above. New Jerusalem is the "hometown" to which we are headed. Spiritual freedom characterizes such citizens from above. "So then, brethren, we are not children of the bondwoman but of the free." The Lord calls us to live by the liberating grace of the Lord Jesus Christ, renouncing all inclinations toward the bondage of self-sufficient legalism. "Stand fast therefore in the liberty by which Christ has made us free, and do not be entangled again with a yoke of bondage."