It is the distinctive position of the Reformation with…

““It is the distinctive position of the Reformation with which, over against Rome, it stands or falls, that that which properly constitutes, defines, and perpetuates in unity a Church, is its doctrine, not its name or organization. While a Church retains its proper identity it retains of necessity its proper doctrine. Deserting its doctrine it loses its identity. The Church is not a body which bears its name like England, or America, which remain equally England and America, whether savage or civilized, Pagan or Christian, Monarchical or Republican. Its name is one which properly indicates its faith--and the faith changing, the Church loses its identity. Pagans may become Mohammedans, but then they are no longer Pagans--they are Mohammedans. Jews may become Christians, but then they are no longer Jews in religion. A Manichean man, or Manichean Church, might become Catholic, but then they would be Manichean no more. A Romish Church is Romish; a Pelagian Church is Pelagian; a Socinian Church is Socinian, though they call themselves Protestant, Evangelical, or Trinitarian. If the whole nominally Lutheran Church on earth should repudiate the Lutheran doctrine, that doctrine would remain as really Lutheran as it ever was. A man, or body of men, may cease to be Lutherans, but a doctrine which is Lutheran once, is Lutheran forever. Hence, now, as from the first, that is not a Lutheran Church, in the proper and historical sense, which cannot ex animo declare that it shares in the accord and unanimity with which each of the Doctrines of the Augsburg Confession was set forth.””

— Charles Porterfield Krauth