Below is a good post from Catholic apologist, Jimmy Akin, on the use of the term, "anathema" in Church Council canons:A reader writes:
Recently I came a cross a web site that claimed that an anathema applies to anyone who affirms an doctrine that is contrary to the kind of anathema issued by Vatican I (that is, the kind that says, “If anyone says X, let him be anathema”).
The same site said that one of the anathemas of Vatican I made a powerful argument against sedevacantists who say that Pius XII was the last valid pope because Vatican I said that St. Peter will have successors to the end of time.
What do you make of these claims?
The claim that anathemas apply to those who contradict the canons of an ecumenical council, whether Vatican I or one of the other councils, is a common and understandable misunderstanding. We haven’t done a very good job about educating people on what the term “anathema” means in this context, and an awful lot of people are under an innocent misimpression.
To put the matter concisely: The term “anathema,” as used in conciliar and canon law documents, refers to a type of excommunication. In particular (as in the 1917 Code of Canon Law), it referred to a type of excommunication that the bishop performed using a special ceremony. This ceremony involved (among other things) the ringing of a bell, the closing of a book, and the snuffing of a candle. Hence the phrase “bell, book, and candle” (that’s where it comes from; it has nothing to do with witchcraft). These collectively symbolized that the ecclesiastical court had made its ruling against the offender and would not reconsider until he repents. There was then another special ritual of reconciliation for the lifting of the anathema.
(BTW, the image is a painting of the excommunication of Robert the Pious of France. That’s not a giant, smoldering cigarette pointing accusingly at him on the floor but the snuffed candle that the bishop’s entourage—seen leaving by the door—has just yanked off its accompanying candle holder.)
Like other excommunications, anathemas didn’t do anything to a person’s soul. It didn’t make him “damned by God” or anything like that. The only man who can make a man damned by God is the man himself. The Church has no such power. An anathema was a formal way of signaling him that he had done something gravely wrong, that he had endangered his own soul, and that he needed to repent. Anathemas, like other excommunications, were thus medicinal penalties, designed to promote healing and reconciliation.
Also like (many) excommunications, anathemas were not automatic. Just because someone, somewhere, uttered a heresy, this did not cause the relevant bishop to drop whatever he was doing and automatically perform the ceremony like a puppet on strings. Instead, if someone committed an ecclesiastical crime that was potentially subject to an anathema the matter had to be reported, investigated, judged, and only after that would the ceremony happen—if it did.


