Here we have that spiritual Mount Zion, the heavenly Jerusalem, described more clearly in Hebrews 12:22-23, "You have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to innumerable angels in festal gathering, and to the assembly of the firstborn who are enrolled in heaven, and to God, the judge of all, and to the spirits of the righteous made perfect." How do I know that it is the spiritual Zion, instead of the physical one? The text itself says that God prefers it over the dwelling places of Israel, which would include the geographical area of Jerusalem. See also Revelation 21:2, 19-27. This is the distinction in the creeds between the "visible church" and the "invisible church."
This Psalm is the inspiration for the hymn, "Glorious things of thee are spoken," by John Newton (who also wrote "Amazing Grace"). Unfortunately, the hymn has been set to the same tune as "Deutschland, Deutschland, uber alles," the national anthem of Nazi Germany, quite contrary to the Psalmist's universalism.
That's what I love about this particular Psalm: its universal view of the prosperity of the Gospel. Men are born the first time citizens of their respective countries, but they are born again the citizens of the Zion of God. The same theme appears in a number of places in the Scriptures, such as Daniel 7:14, "To Him was given dominion and glory and a kingdom, that all peoples, nations, and languages should serve Him," and again in Revelation 7:9, "...behold, a great multitude that no one could number, from every nation, from all tribes and peoples and languages, standing before the throne and before the Lamb, clothed in white robes, with palm branches in their hands."
We must seek the power of the Holy Spirit to make our vision as broad as His is! Too often, evangelism and missions in today's Church mean nothing more than seeking to add a few individuals, here and there. The Prophets saw missions as bringing entire peoples into God's Church, for the glory of Christ alone! Scottish Presbyterian Iain Murray's book "Puritan Hope" examines the impact when that vision takes hold of the Church. Our narrowness has deprived Jesus Christ of the honor and glory to which He is due.