ESV - 26 But the Jerusalem above is free, and she is our mother.
In order to understand Gal 4:26, I need to back up to Gal 4:24, 25 to develop the context. Paul introduces an allegory—a Jewish “midrash”—by way of the biblical narrative about Father Abraham and his offspring. Whatever the reasons for introducing this allegory into his letter at this point, the interpretation of the allegory is quite to the point: a line of demarcation is being drawn in the sand between who is a genuine covenant member and who is not. The son of Abraham by the slave woman (understood to be Ishmael, even though he is not named directly) is likened to those seeking to be justified by human means, by the works of the Law, by circumcision, by legal Jewish identity. Comparatively, the son of Abraham by the free woman (Isaac) is likened to those seeking to be justified by faith in Yeshua (Jesus) as the promised Messiah, without becoming Jewish first. To strengthen the truth of his illustration, Paul mentions that Ishmael was born when Abraham succumbed to his flesh—the way ordinary human beings procreate, while Isaac was born, not according to human effort, but by divine fiat after Abraham and Sarah were in reality too old to physically copulate for the sake of creating children. The Greek word for ‘allegorically’ in Gal 4:24 is the root word allegoreo ἀλληγορέω, from where we get our English word allegory. Paul now reveals the core truth of his homily by explaining that he is referring to two opposing covenants, illustrated using (unnamed) Sarah, and (named) Hagar. Paul also wants his readers to understand that to expect right standing with God according to the flesh—according to Jewish social status—is to be identified with a covenant of slavery, the covenant with Hagar and her offspring. This covenant with Hagar and her offspring relates to where the Torah of Moses was given because that is where the present Judaisms of Paul’s day all looked to for the origins of the Nation of Isra'el as a people, because it is there that God covenantally “married” as it were, his bride Isra'el. Even though Paul specifically states that Hagar=Mount Sinai and corresponds to present city Jerusalem, oddly enough, Paul does not mention Sarah by name, nor does he say which mountain and city she stands for (if any). What he does say specifically is that the Jerusalem that is above is free (in opposition to the slave-city earthly Jerusalem), and that this heavenly Jerusalem is our mother (more on these distinctions below). I’m sure in Paul’s mind, it is a sad declaration that his beloved and beautiful earthly Zion, the City of God spoken of in Psalm 87:3, has to be identified in his allegory as a city in slavery with her children, in order for his readers to come to their senses. But this is the length to which Paul will go to shock his readers into reality. To flirt with the prospect of going through conversion for the wrong reasons is to be seen in God’s eyes as going back into slavery. It is possible that one could understand these verses as proof positive that the Old Covenant stemming from Mount Sinai represents slavery and must be replaced by the New Covenant stemming from the Heavenly Jerusalem that offers freedom, and this would be true only if we interpret the terms "old covenant" as "old nature" and "new covenant" as "new nature." Indeed, all things DO become new in Christ (2 Cor 5:17). *Excerpted from my Exegeting Galatians Messianic Jewish Commentary available in the eBible reading plans here: http://ebible.com/plans/landing/608