In the Old Testament, God called the Jews to be his special people, and Jerusalem was called the city of God.
But Psalm 87 looks to a future Jerusalem, a heavenly one. (Hebrews 12:22-23)
What had to be amazing to the Jews who read this psalm was that it points to a time when even the Jews’ greatest enemies would be counted among God’s people.
People from Rahab, (i.e. Egypt), Babylon, and Philistia, would become God’s people.
People from Tyre and Cush (i.e. Ethiopia) would also be counted among God’s people.
God will say of them, “They are not outsiders. These people were actually born in my city. They are full-fledged citizens.” (Psalm 87:5-6)
John writes about this in Revelation.
After this I looked, and there was a vast multitude from every nation, tribe, people, and language, which no one could number, standing before the throne and before the Lamb.
They were clothed in white robes with palm branches in their hands. And they cried out in a loud voice:
Salvation belongs to our God,
who is seated on the throne,
and to the Lamb! (Revelation 7:9-10)
So remember who you are.
Who are you?
You are his.
It doesn’t matter if you’re Japanese, American, Australian, Chinese, Korean, or whatever you may be. You were born again into the kingdom of God when you put your trust in Jesus.
Paul puts it this way,
(When you were ‘outsiders’), you were without Christ, excluded from the citizenship of Israel, and foreigners to the covenants of promise, without hope and without God in the world.
But now in Christ Jesus, you who were far away have been brought near by the blood of Christ…
He came and proclaimed the good news of peace to you who were far away and peace to those who were near. For through him we both have access in one Spirit to the Father.
So, then, you are no longer foreigners and strangers, but fellow citizens with the saints, and members of God’s household… (Ephesians 2:12-13, 17-19)
So let us always remember who we are and rejoice with all of God’s people, singing,
My whole source of joy is in you. (Psalm 87:7)
Moment to Moment (Bible blog) 