It really is just this easy: “The Heretic Excludes Himself From the Church”

B.  The Heretic Excludes Himself From the Church

In subscribing to heresy, the heretic excludes himself from the Church. As Saint Paul states, he is “condemned by his own judgment” (Tit. 3:10–11).

Saint Jerome comments on this text from Saint Paul saying: “Therefore it is said that the heretic has condemned himself; for the fornicator, the adulterer, the murderer and the other sinners are expelled from the Church by the priests; but the heretics pronounce sentence against themselves, excluding themselves from the Church spontaneously; this exclusion is their condemnation by their own conscience.”¹⁶

Saint Augustine comments along the same line: “Separate yourselves from the members of the Church, separate yourself from her Body. But why am I going to tell them to separate from the Church when they have already done so? In effect, they are heretics; they are already outside the Church.”¹⁷

Finally, Pope Pius XII affirms that no sin “of its own nature . . . severs a man from the Body of the Church as does schism or heresy or apostasy.”¹⁸

The heretic excludes himself from the Church, and no intervention is necessary on the part of the Authority. The heretic dictates his own condemnatory sentence.

The abandonment of the Catholic faith entails a tacit resignation of any ecclesiastical office, since those who are no longer part of the Church cannot enjoy jurisdiction in it.

The importance of this theological-canonical doctrine is not strictly academic. It is crucial in the study of the theological hypothesis of a heretic pope, as will be seen in a later article.

https://www.tfp.org/the-heretic-excludes-himself-from-the-church-being-condemned-by-his-own-judgment/