ROME -- The Roman Catholic Church rarely talks these days of heresy, a verdict that carries eerie echoes of the Inquisition and ends in automatic excommunication, the harshest penalty in canon law. And so theologians took note when the Vatican's doctrinal authorities found a 72-year-old Sri Lankan priest and scholar guilty of having "deviated from the integrity of the truth of the Catholic faith," and formally cast him out of the communion of the church last week.

The harshness of the verdict and the punishment promise to make the case of the Rev. Tissa Balasuriya, something of a cause celebre among Third World theologians who have followed his ordeal before the Vatican authorities with both sympathy and dread. The only other public case of excommunication in recent times was against Archbishop Marcel Lefebvre in 1988, after he continued to flout the reforms of the Second Vatican Council.

Balasuriya was accused of challenging such basic Roman Catholic beliefs as original sin and the immaculate conception.

Reached by telephone on Monday in Colombo, the Sri Lankan capital, he said calls and telegrams are coming in from around the world, as well as a petition of support signed by colleagues from the Ecumenical Association of Third World Theologians.

"They all say they will always treat me as a priest and a Catholic," said Balasuriya, who said his four-year battle with the defenders of Catholic orthodoxy has made him "more Catholic than ever."

Balasuriya, a member of the missionary order of the Oblates of Mary Immaculate for 51 years, embraces views that have been labeled "religious relativism," according to which no faith has a unique claim to the truth, and no spiritual figure can claim to be the only savior.

The keepers of the faith at the Vatican have been working to put down a rising tide of "relativism," recently described by one top church official as the gravest threat to dogmatic faith since Marxism.

Balasuriya's defiance has set his case apart from other disputes that have pitted theologians against Cardinal Joseph Ratzinger, the formidable head of the Congregation for the Doctrine of the Faith, which adjudicates doctrinal matters.

The strict discipline imposed by Pope John Paul II has been exercised on the Swiss theologian Hans Kueng, a professor at Tuebingen University in Germany; the Rev. Charles E. Curran, who taught at Catholic University in Washington, D.C.; and the school of liberation theologians from Latin America whose anti-establishment, populist views often overlapped with leftist social ideals in the 1970s and '80s. The Vatican stopped short of excommunicating Kueng and Curran, and only barred them from teaching Catholic theology.

"This is much tougher," Kueng said on Monday in a telephone interview about Balasuriya's case, "perhaps because he is a Third World theologian. It is very serious for this man, and it is very unjust, but it is the consequence of the system. This is the system as it works, and as it will work as long as Catholicism doesn't get rid of a doctrine that says that the pope is always right."

In an address to heads of doctrinal commissions from around the world, in May in Guadalajara, Mexico, Ratzinger, who is seen as Pope John Paul II's principal doctrinal watchdog, laid out the dangers of a blend of the West's secular relativism and the "philosophical and religious intuitions of Asia, especially and surprisingly with those of the Indian subcontinent."

From the marriage of these trends, he said, is born the religious relativism that is unacceptable for the Catholic Church.

"The faith, together with its practice, either comes to us from the Lord through his church and the sacramental ministry, or it does not exist in absolute," Ratzinger said.

By excommunicating Balasuriya, the Vatican has sent its message in an even more forceful way.

"They want to menace everyone else who is in this field," Kueng said. "Unfortunately it is an efficient method because now every stupid theologian in India can accuse others of defending what Father Balasuriya was saying."

The case against Balasuriya, who is a sociologist as well as a theologian, began in 1993, when the Catholic Bishops' Conference in Sri Lanka called for an investigation into his latest book, "Mary and Human Liberation." The book took a critical look at the cult of the Virgin Mary, in particular her image as a "Mary of the capitalist, patriarchal, colonialist first world of Christendom" whose "perpetual virginity" makes her "a dehydrated figure who is not quite human."

Balasuriya, who has been promoting a dialogue among the island nation's religions, argued in that and other books that Christianity and Catholicism must go further to acknowledge the legitimacy of other faiths.

By July 1994, the Congregation for the Doctrine of the Faith compiled an 11-page critique of Balasuriya's views, much of which he later dismissed as a "misrepresentation." In due course, he sent off a 55-page response to which he received a one-word reply: "Unsatisfactory."

And so the exchange continued, with never an opportunity for the constructive dialogue on religious issues that Balasuriya said he always wanted. "There has been no face-to-face contact with the unknown officials at the congregation," he said in a statement issued on Monday.

He argued that the Vatican, halfway around the world in overwhelmingly Catholic Italy, is in no position to judge the rights and wrongs of scholars working in multi-denominational cultures like Sri Lanka, where most people, about 69 percent, are Buddhists, about 15 percent are Hindus, and Christians and Muslims each make up less than 8 percent of the population.

"This has raised the question of whether or not the local church should not be solving these issues, and not unknown persons in Rome, dealing in Italian," he said. "Due process in the church must be clarified."

Finally, in May 1996, the Vatican, clearly exasperated by the drawn-out epistolary exchange, sent Balasuriya a long "profession of faith," which it insisted he sign "to verify if you accept the truths" taught by the Catholic Church. Included was a paragraph explicitly acknowledging the Vatican's hardline position against the ordination of women.

For this and other reasons, Balasuriya refused to sign the specially written profession of faith, and opted instead to sign a similar one, without the clause on women priests. That approach was rejected by the Vatican, and after a last-minute appeal to Pope John Paul II himself, the congregation started to move slowly but inexorably toward its final judgment, officially rendered on Jan. 2 and published on Jan. 5.

For other members of the Oblates order, the fate of Balasuriya has been a painful episode, pitting personal loyalties against faith. "I love my order; the fraternal bonds are very strong," said the Rev. Alexandre Tache, procurator-general of the order based here in Rome, "but you have to respect the mission of the church. The pope and the bishops have a responsibility for teaching by the Scriptures, for interpreting by tradition."