New Birth; New Jerusalem

To help us understand Psalm 87, we go to Galatians 4:24 which indicates that there are two Zions - an earthly and a heavenly. It is only a spiritual birth that registers one in the heavenly Jerusalem. Even some from the pagan nations will be "born in her." Romans 15:8-12 is a series of quotes from the OT showing that the the coming of the Gentiles to Christ was prophesied there. It is the new birth that alone qualifies us to be a citizen of Zion.