Galatians 4:26

Jerusalem which is above. As literal Jerusalem represents Israel as a nation, so “Jerusalem which is above” represents the Christian church (see Heb. 12:22, 23), the new chosen nation (1 Peter 2:9). The New Jerusalem is the capital of the kingdom of glory (see Rev. 21:2; Heb. 11:10), but Paul here uses Jerusalem in a figurative sense; the contrast is between Judaism and Christianity. The former is “in bondage”; the latter is “free.”

Free. That is, “free” from the “schoolmaster” of ch. 3:24, 25, from the bondage of ch. 4:3, and from the status of slavery of vs. 22-25.

Mother. In figurative language the Jews often spoke of literal Jerusalem — meaning the nation of Israel — as the “mother” of the living generation of individuals composing the nation. In a similar sense, the historic Christian church is the “mother” of living Christians.

Us all. Probably a reference to the “all” of ch. 3:26, meaning Gentiles and Jews. The middle wall of partition between the Jew and Gentile has been removed by Christ (see Eph. 2:12-22). This good news of unity by faith in Christ brought great joy to the Gentiles, for they were now accepted on an equality with the Jews (see Acts 13:44-48).