XVII. From the faith of history which exhibits multiple worshipers of God and witnesses of the truth, who repeatedly opposed themselves to the papistical errors and bore testimony to the truth. For if there are granted many who by words, deeds and writings disturbed the Roman court on account of his errors, idolatries and tyranny and who for that cause were treated in the most unworthy manner and exposed to the most cruel persecutions, there is no doubt that they constituted the true church which we seek. Now that there were innumerable such persons the catalogues of Magdeburg, of Illyricus, Plessius, Fox and others prove, which give the names and writings of those warning the condition of the church under the papacy, while seeking and urging a Reformation. Ussher Also should be examined (de Christianarum ecclesiam in Occidentis 6 , pp. 142-74); and Voetius, Where he proves the succession of the true faith and church under the New Testament through all ages up to the Reformation and brings forward various examples of the pious lamenting and protesting against the errors of the papacy (Desperata causa papatus novissime 3.2 , 530-703).
XVIII. From more similar examples of the church both of the Old and of the New Testaments. In the Old Testament: (a) of the church in Egypt after the death of Joseph and his brothers Ezk 16); (a) of the Israelite church under Elijah, who complains that he is left alone, God however reserving for himself 7000 (1 K 19:18); (c) Of the church in Samaria after the 10 tribes had been carried away to Assyria (2 Ch 30:11; 34:33); (d) of the Jewish church in the Babylonian captivity, with which is compared the state of the church under the tyranny of antichrist (Rev. 17; 18). Under the New Testament: at the time of the birth of Christ, the church was not to be found among the scribes, Pharisees and pontiffs (who glory in the name of the church, but who were the enemies of God and Christ), but in a few pious persons and believers waiting for the redemption of Israel. At the time of Paul, the Jewish church was reduced to a few elect with Paul, others remaining hardened and unbelievers (Rom. 11:1, 5). What wonder, then, if we say that the true church was equally in the midst of the spiritual Babylon and Egypt, stripped of her distinctive marks and external ornaments?
Francis Turretin, Institutes of Elenctic Theology, 18.10.17-18.