Apologeticae sive Theologiae Fundamentalis, Tomus II (Pars Altera): Demonstratio Catholica

It is to be presumed that the Church excels by the confession of one faith, since it follows the one Christ as teacher and is subject to the one magisterium established by Christ. The following expressly require the unity of the symbolic confession:

1. Christ. Christ commanded the apostles to "teach all nations", and indeed to "teach all things, whatsoever He commanded", and to preach the "gospel" in its entirety "to every creature".¹ To these precepts He simply adds: "He who believes and is baptized will be saved; but he who does not believe will be condemned."² Therefore the teaching Church is bound to preach the same evangelical doctrine everywhere and to all men, and the learning Church, in its entirety and everywhere, is bound to profess the same evangelical doctrine. And this with the added sanction of eternal salvation and eternal punishment. From this there undeniably arises the unity of the symbolic confession, whereby every heresy is kept away from the Church.

2. Paul. Paul, solicitous about the unity of faith, teaches the Ephesians: "One Lord, one faith, one baptism, one God and Father of all"³ He reproaches the Galatians: "I marvel that you are so quickly transferred from him who called you into the grace of Christ, to another gospel, which is not another; but there are some who trouble you and want to pervert the gospel of Christ. But even if we or an angel from heaven preach to you a gospel other than that which we preached to you, let him be anathema."⁴ He warns Titus: "Avoid a heretical man after one and a second admonition, knowing that one who is such is subverted and sins, being condemned by his own judgment."⁵ He entreats Timothy: "O Timothy, guard the deposit, avoiding profane novelties of words and oppositions of knowledge falsely so called, which some promising have erred concerning the faith."⁶

3. Christian antiquity. From the innumerable testimonies that bear upon this matter we draw out these few. St. Irenaeus says: "The true and universal Church holds one and the same faith throughout the whole world."⁷ He describes the preaching of the Church as "everywhere constant and equally persevering".⁸ Theodoret explains: "Just as any city contains within itself many houses divided among themselves and yet is called one city, so the churches are infinite and innumerable, on the islands and on the continent, and at the same time all are brought back into one, united by the consonance of true dogmas."⁹ St. Augustine writes about the Church: "The raiment of this queen [the Church] … is precious and varied: the sacraments of doctrine in all the various languages … But just as all the variety of the garment agrees in unity, so too all languages [agree] unto one faith … Whatever the variety of languages, one gold is preached: not diverse gold, but variety from gold. For all languages preach the same wisdom, the same doctrine and discipline. Variety in the languages, gold in the sentences."¹⁰ Above the testimonies of these and of other individual fathers stand the creeds prescribed to the whole Church by the first ecumenical councils for the preservation of unity. Such a creed the first Nicene council already prescribed to be professed, adding an anathema against those who would believe otherwise.¹¹

By these texts of Christ, of Paul, and of antiquity, the unity of the symbolic confession is not only demanded but also defined, so that it extends to the whole revealed doctrine and to it alone. To the whole revealed doctrine: whence certain Protestants wrongly contend that for the unity of faith in the Church, and likewise for attaining eternal salvation, agreement on the "fundamental" articles suffices, while the "non-fundamental" ones can be denied without detriment to unity and salvation.¹² To the revealed doctrine alone: whence the unity of the Church can be perfect, although various ecclesiastical laws, various liturgical forms, various theological opinions, etc. are found. Provided that all things which Christ revealed are preached and believed everywhere and by all.