3 Who are these? “They shall stand fast for ever, who dwell in Jerusalem”. If we understand this earthly Jerusalem, all who dwelt therein have been excluded by wars and by the destruction of the city: thou now seekest a Jew in the city of Jerusalem, and findest him not. Why then will “they that dwell in Jerusalem not be moved for ever,” save because there is another Jerusalem, of which you are wont to hear much? She is our mother, for whom we sigh and groan in this pilgrimage, that we may return unto her....They then who dwell therein “shall never be moved.” But they who dwelt in that earthly Jerusalem, have been moved; first in heart, afterwards by exile. When they were moved in heart and fell, then they crucified the King of the heavenly Jerusalem herself; they were already spiritually without, and shut out of doors their very King. For they cast Him out without their city, and crucified Him without. He too cast them out of His city, that is, of the everlasting Jerusalem, the Mother of us all, who is in Heaven.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)