The decision provided fresh fuel for critics who charge that Benedict's four-year-old papacy has increasingly moved in line with traditionalists who are hostile to the sweeping reforms of the Second Vatican Council in the 1960s that sought to create a more modern and open church.
A theologian who has grappled with the church's diminished status in a secular world, Benedict has sought to foster a more ardent, if smaller, church over one with looser faith.
But while the revocation may heal one internal rift, it may also open a broader wound, alienating the church's more liberal adherents and jeopardizing 50 years of Vatican efforts to ease tensions with Jewish groups.
Among the men reinstated Saturday was Richard Williamson, a British-born cleric who in an interview last week said he did not believe that six million Jews died in the Nazi gas chambers. He has also given interviews saying that the United States government staged the Sept. 11 attacks as a pretext to invade Afghanistan.
The four reinstated men are members of the Society of St. Pius X, which was founded by a French archbishop, Marcel Lefebvre, in 1970 as a protest against the modernizing reforms of the Second Vatican Council, also called Vatican II. Archbishop Lefebvre made the men bishops in unsanctioned consecrations in Switzerland in 1988, prompting the immediate excommunication of all five by Pope John Paul II.
Later that year, Benedict, then Cardinal Joseph Ratzinger, sought to regularize the church's relationship with the society. And as pope, he has made reinstating the Lefebvrists an important personal cause.
Indeed, even though the Society has given no public signs that it would reverse its rejection of Vatican II, one Vatican official, speaking on condition of anonymity on Saturday because talks were continuing, said that the Vatican was willing to discuss making the group a personal prelature. Pope John Paul II did the same with another conservative group, Opus Dei.
In a public statement Saturday, the Vatican said that the pope would reconsider whether to formally affirm the four men as full bishops, but it referred to the men by that title. It said talks would seek to resolve the "open questions" in the church's relationship with the society.
In recent years, Benedict has made other concessions to the followers of Archbishop Lefebvre, who died in 1991. The overtures including allowing the broader recitation of the Latin Mass, which was made optional in the 1960s and includes a Good Friday prayer calling for the conversion of Jews.
Chester Gillis, who holds the Amaturo chair in Catholic studies at Georgetown University, said that both Benedict and John Paul II before him had tried for years to bring these traditionalists back into the church, partly out of concern that their movement might grow and create an entrenched parallel church.
"I don't think the Vatican doesn't care about Jewish-Christian relations, but at least it appears that internal church matters trump external relations," he said. "They're thinking, let's heal our own house, whatever the consequences are externally."
The recent comments by Bishop Williamson, who led a seminary in Ridgefield, Conn., in the 1980s and later moved to a seminary in Argentina, inevitably overshadowed the debate about traditional and liberal strains in the Roman Catholic Church.
In a November interview broadcast on Swedish television last week and widely available on the Internet, the bishop said that he believed that "the historical evidence" was strongly against the conclusion that millions of Jews had been "deliberately gassed in gas chambers as a deliberate policy of Adolf Hitler."
The Vatican spokesman, the Rev. Federico Lombardi, said Saturday that Bishop Williamson's comments had nothing to do with the pope's decision to welcome the schismatic bishops back into the fold. He added, "These are declarations that we don't share in any way."
Father Lombardi called the revocation of the excommunications a fundamental step toward the unity of the church, after two decades of rift. "We have to consider it very positive news," he said. He said that Benedict had "greatly suffered" at the group's excommunication and had long been "a protagonist in relations with Lefebvre."
Jewish groups criticized the decision to reinstate the men on Saturday, and the decision is sure to complicate talks between the Vatican and Israeli officials about a proposed papal trip to the Holy Land this year.
In a statement, the Anti-Defamation League said that lifting Bishop Williamson's excommunication "undermines the strong relationship between Catholics and Jews that flourished under Pope John Paul II and which Pope Benedict XVI said he would continue when he came into his papacy."
Abraham Foxman, the A.D.L.'s national director, added that the decree "sends a terrible message to Catholics around the world that there is room in the church for those who would undermine the church's teachings and who would foster disdain and contempt for other religions, particularly Judaism. Given the centuries-long history of anti-Semitism in the church, this is a most troubling setback."
In a statement released Friday, Rabbi David Rosen, the director of the International Jewish Committee for Interreligious Consultations, said, "We urgently call on the Vatican to reiterate its unqualified repudiation and condemnation of all and any Holocaust denial."
In revoking the excommunications, the Vatican said it was responding to a letter sent in December by the director of the Society of Pius X, in which the bishops said they were "firmly determined to remain Catholic and to put all our efforts to the service of the church."
The letter appeared to stop short of saying that the society would embrace, or even accept, the reforms of Vatican II.
"This is certainly a major concession to the traditionalists, part of a long effort by Rome to heal the only formal schism after Vatican II," said John L. Allen Jr., a columnist for the National Catholic Reporter. "Politically, this certainly emboldens the conservative reading of the council and emphasizes what Benedict XVI has repeatedly called the 'continuity' of Vatican II with earlier periods of church history."
In a letter sent to followers on Saturday, Bishop Bernard Fellay, the director of the Society of St. Pius X and one of the four reinstated, said: "Thanks to this gesture, Catholics attached to tradition throughout the world will no longer be unjustly stigmatized and condemned for having kept the faith of their fathers."
He added that the society welcomed an opportunity to talk with the Vatican "to explain the fundamental doctrinal reasons which it believes to be at the origin of the present difficulties of the church."
George Weigel, a biographer of John Paul II, said he was troubled by Bishop Fellay's implication in his letter that the schismatic group represented the tradition, while "the rest of us are, somehow, the true schismatics."
He added: "It is not easy to see how the unity of the Church will be enhanced unless the Lefebvrists accept Vatican II's teaching on the nature of the Church, on religious freedom, and on the evil of anti-Semitism, explicitly and without qualification; otherwise, you get cafeteria Catholicism on the far right, as we already have on the left."
Laurie Goodstein contributed reporting from New York.
