Bishop Lefebvre vacillated on calling the Pope Antichrist, or raising the sedevacantist argument, but he did certainly say that from time to time.
Here’s an extract from a long article that discusses the matter, one of several places in the article where the topic comes up:
Was Lefebvre a sede vacantist? It seems that it depended on his mood, or on the audience he was addressing. In 1980 he wrote to the Holy Father and protested, “I have no hesitation regarding the legitimacy or the validity of Your election. I have already had to condemn these ideas and I continue to do so in the face of some seminarians who allow themselves to be influenced by ecclesiastics outside the Fraternity.” But in his various tours, the ex-Lefebvrite priest informs me, he would speak a “faithful-to-the-pope” line to conservative Catholics, and a suggestively sede vacantist line when talking to radical traditionalists. Like any politician, he played to the audience.
But he threw caution to the winds in the preface of his 1987 letter to the four bishops-to-be. Here he calls the pope an Antichrist, which is a vivid way -of saying the papal seat is empty. Moreover, there exists an audiocassette tape of a Lefebvre sermon given shortly after John Paul II’s 1986 Assisi peace convocation. Basing his charges on that ecumenical gathering, the archbishop says, “I think that when a Pope or bishop honors God in this non-Catholic way, they have the intention of going to God as a non-Catholic, thereby renouncing the Catholic faith. Never has it happened in the Church before that he who sits on the throne of Peter has participated in the cult of false gods. Are we then obliged to believe that this Pope is not Pope? Because it seems impossible that a Pope could be a public and formal heretic.”
The sede vacantist question brings us back to the United States. Three previously Lefebvrite priests, Fathers Cekada, Dolan and Sanborn, have now split from the Pius V Society, which Fr. Kelly had formed when he broke with Lefebvre, to become involved in varying degrees with the cult at Mount St. Michael, whose pretense to Catholicism rests on its connection to the Bishop Thuc (of South Vietnam) lineage. As Lefebvrite seminarians proposed for the priesthood back in the 1970s, these three encountered opposition because of their openly expressed sede vacantism. A delegation of American priests warned Lefebvre.
But the Archbishop. knowing their standpoint ordained them anyway. Then, in 1983, Lefebvre used that excuse, sede vacantism, to kick Fr. Kelly and the others out of the Society. The accusation must have rung hollow, given Lefebvre’s own leanings. Especially since Richard Williamson, openly a sede vacantist as a seminarian at Econe, was later made bishop for North America.
The full article is at:
http://sspx.agenda.tripod.com/id9.html
I was speaking from memory in my earlier post. We lived at one time near the seminary of SSPX in Ridgefield, CT, and I read quite a bit about the matter, pro and con. I was not fond of Vatican II and what came after it, but after considerable investigation, I stuck with the Church—warts and all—because it is the Church.