Paul uses the Hebrew form Ἱερουσαλὴμ in preference to the Greek Ἱεροσόλυμα, which occurs Gal 1:17, Gal 1:18; Gal 2:1. The phrase Jerusalem which is above was familiar to the rabbinical teachers, who conceived the heavenly Jerusalem as the archetype of the earthly. On the establishment of Messiah's kingdom, the heavenly archetype would be let down to earth, and would be the capital of the messianic theocracy. Comp. Heb 11:10; Heb 12:22; Heb 13:14; Rev 3:12, Rev 21:2. Paul here means the messianic kingdom of Christ, partially realized in the Christian church, but to be fully realized only at the second coming of the Lord. For ἄνω, comp. Phi 3:14; Col 3:1, Col 3:2.
Free (ἐλευθέρα)
Independent of the Mosaic law; in contrast with the earthly Jerusalem, which, like Hagar, is in bondage. The Jerusalem above therefore answers to Sarah.
Which is (ἥτις ἐστὶν)
The double relative refers to the Jerusalem which is above, not to free. That Jerusalem, as that which is our mother, is free.
The mother of us all
Render, our mother. Πάντων all does not belong in the text.