We had met these precise words before in Revelation 21:2. The repetition underscores the significance of this city’s origin as God’s own work. As we consider the details of what John sees, we need to bear in mind that the word “coming down” does not describe completed action but ongoing activity, for in John’s day (as today) the holy city (= church) was not yet complete. Further, her heavenly identity informs the next phrase “having the glory of God.”
10 And he carried me away in the Spirit to a great, high mountain, and showed me the holy city Jerusalem coming down out of heaven from God,