Yet it ought to be observed, that we cannot become acceptable to God without being united in one and the same faith, that is, without being members of the Church; for it is not necessary for us to run to Jerusalem, or to Mount Zion, because in the present day Zion is as wide and extensive as the whole world, which is entirely devoted to God. All that is necessary therefore is, that the same faith dwell in us, and that we be joined together by the bond of love. If this be wanting, every thing about us is heathen, and we have nothing that is sacred or holy.
John Calvin, Commentary on the Book of the Prophet Isaiah: Volume Second, trans. William Pringle (Geneva, 1551) in Calvin’s Commentaries (22 vols, Grand Rapids: Baker, 1993), 7: 45-46.