Heretics That Deny Even One Dogma Fall Outside the Catholic Church Until They Recant

The Catholic Church teaches, and has always taught, that one of the essential marks of the Church is unity of faith and obedience. (As the Apostle Paul phrased it "One Lord, One Faith, One Baptism" Ephesians 4:5) This unity is so powerful, that if a man were to become a heretic and deny a dogma of the faith, he would by that very fact sever himself from the body of the Church and fall outside of the Church. To fall outside of the Church, one simply has to deny even one single dogma. If even one doctrine or dogma taught by the Church is denied or doubted, one becomes a heretic and falls outside of the Church. Formal heretics who knowingly deny truth are outside the Church. Even material heretics who hold a true dogma to be false in ignorance are outside of the Church because they no longer have unity of faith. Being outside, a heretic's condemnation is assured unless one's excommunication is lifted.

First- What must be believed by the faithful Catholic?

"Therefore, brethren, stand fast; and hold the traditions which you have learned, whether by word, or by our epistle." -St. Paul, 2 Thess. 2:14

What happens when a Catholic does not believe these things, after hearing or coming to an awareness of the truth? He becomes a heretic:

"The Church, founded on these principles and mindful of her office, has done nothing with greater zeal and endeavour than she has displayed in guarding the integrity of the faith. Hence she regarded as rebels and expelled from the ranks of her children all who held beliefs on any point of doctrine different from her own. The Arians, the Montanists, the Novatians, the Quartodecimans, the Eutychians, did not certainly reject all Catholic doctrine: they abandoned only a certain portion of it. Still who does not know that they were declared heretics and banished from the bosom of the Church? In like manner were condemned all authors of heretical tenets who followed them in subsequent ages. "There can be nothing more dangerous than those heretics who admit nearly the whole cycle of doctrine, and yet by one word, as with a drop of poison, infect the real and simple faith taught by our Lord and handed down by Apostolic tradition" (Auctor Tract. de Fide Orthodoxa contra Arianos).

The practice of the Church has always been the same, as is shown by the unanimous teaching of the Fathers, who were wont to hold as outside Catholic communion, and alien to the Church, whoever would recede in the least degree from any point of doctrine proposed by her authoritative Magisterium. Epiphanius, Augustine, Theodore :, drew up a long list of the heresies of their times. St. Augustine notes that other heresies may spring up, to a single one of which, should any one give his assent, he is by the very fact cut off from Catholic unity. "No one who merely disbelieves in all (these heresies) can for that reason regard himself as a Catholic or call himself one. For there may be or may arise some other heresies, which are not set out in this work of ours, and, if any one holds to one single one of these he is not a Catholic" (S. Augustinus, De Haeresibus, n. 88).

The need of this divinely instituted means for the preservation of unity, about which we speak is urged by St. Paul in his epistle to the Ephesians. In this he first admonishes them to preserve with every care concord of minds: "Solicitous to keep the unity of the Spirit in the bond of peace" (Eph. iv., 3, et seq.). And as souls cannot be perfectly united in charity unless minds agree in faith, he wishes all to hold the same faith: "One Lord, one faith," and this so perfectly one as to prevent all danger of error." Pope Leo XIII, Satis Cognitum, 1896 (infallible)

"The Holy Roman Church condemns, disapproves, anathematizes, and declares to be separated from the Body of Christ, which is the Church, everyone who holds any contrary opinions." Pope Eugenius IV, the Council of Florence, Feb. 4, 1442 (infallible).

"Any who dare to compose or bring forth or produce another creed for the benefit of those who wish to turn from Hellenism or Judaism or some other heresy to the knowledge of the truth, if they are bishops or clerics they should be deprived of their respective charges and if they are laymen they are to be anathematised." -Council of Ephesus (infallible)

"Since we have formulated these things with all possible accuracy and attention, the sacred and universal synod decreed that no one is permitted to produce, or even to write down or compose, any other creed or to think or teach otherwise. As for those who dare either to compose another creed or even to promulgate or teach or hand down another creed for those who wish to convert to a recognition of the truth from Hellenism or from Judaism, or from any kind of heresy at all: if they be bishops or clerics, the bishops are to be deposed from the episcopacy and the clerics from the clergy; if they be monks or layfolk, they are to be anathematised." - Council of Chalcedon (451 A.D.) (infallible)

"So now that these points have been formulated by us with all precision in every respect and with all care, we definitely state that it is not allowable for anyone to produce another faith, that is, to write or to compose or to consider or to teach others; those who dare to compose another faith, or to support or to teach or to hand on another creed to those who wish to turn to knowledge of the truth, whether from Hellenism or Judaism or indeed from any heresy whatsoever, or to introduce novelty of speech, that is, invention of terms, so as to overturn what has now been defined by us, such persons, if they are bishops or clerics, are deprived of their episcopacy or clerical rank, and if they are monks or layfolk they are excommunicated." -Council of Constantinople (680-681 A.D.) (infallible)

"We decree that those who give credence to the teachings of heretics, as well as those who receive, defend, or patronize them, are excommunicated..." Pope Innocent III, IV Lateran Council, 1215 A.D. (infallible)