The nations on the new earth around New Jerusalem walk by the light of New Jerusalem (Rev. 21:24), bring their glory and honor into it (Rev. 21:26), and are healed by the leaves of the tree of life (Rev. 22:2). God’s people are not these nations because the Lord Jesus has purchased us for God, redeeming us “out of every tribe and tongue and people and nation” (Rev. 5:9).
Galatians 3 says we are justified by faith (v. 24), we are sons of God through faith in Christ Jesus (v. 26), and we were baptized into Christ and put Him on (v. 27). Because of these divine steps, verse 28 says “There cannot be Jew nor Greek, there cannot be slave nor free man, there cannot be male and female; for you are all one in Christ Jesus.”
In Christ Jesus (and in New Jerusalem) there is no distinction between nationalities, no distinction between social statuses, and no distinction between make and female. Galatians 3:28 does not say “there should not be” but “there cannot be.” In Christ and in New Jerusalem there are no nationalities.
First Corinthians 12:12 reminds us that our human body is one with many members, then tells us, “so also is the Christ.” Verse 13 continues, “For also in one Spirit we were all baptized into one Body, whether Jews or Greeks, whether slaves or free, and were all given to drink one Spirit.”
All of us are one Body in Christ, not by our determination, but by His baptizing us in one Spirit into the one Body. In this Body there are no separating nationalities; we are one Body in Him. This reality continues into New Jerusalem, where eternally there is oneness in Christ and no nationalities.