Obituary : Fr. Jacques Dupuis, S.J. - Promoted pluralism in the Catholic Churc

Father Jacques Dupuis, who has died aged 81, was a theologian who, to his horror and distress, became one of the many modern Roman Catholic thinkers who were investigated by Pope John Paul's Vatican on suspicion of heresy.

In October 1998, the Congregation for the Doctrine of the Faith, the Vatican "ministry" that is responsible for enforcing orthodoxy, told his superiors that it had opened an inquiry into his pioneering work, Toward A Christian Theology Of Religious Pluralism, which was published in 1997.

Father Dupuis, a Belgian Jesuit who spent 34 years of his life in India, was one of the Catholic church's leading experts on what many theologians regard as the key issue for debate in a globalising world, the relationship between Christianity and other faiths. Towards A Christian Theology Of Religious Pluralism scrutinised Rome's long-standing claim: Extra ecclesiam nulla salus (outside the Church there is no salvation).

Father Dupuis argued that it was redundant to question whether there was "salvation" for members of other religious traditions. What remained to be resolved was how, in God's grand plan, other religions mediated salvation for their members.

Officials at the Congregation for the Doctrine of the Faith were not alone in seeing this as a possible challenge to the proposition that the Roman Catholic Church offers the only sure path to redemption.

The effect of the investigation was dramatic; it ended the academic career of Father Dupuis, and he was reported to have spent two weeks in hospital after receiving the Congregation's notification. At the time, he was lecturing at the Gregorian University in Rome. He was immediately relieved of his teaching duties by the head of the order, Hans-Peter Kolvenbach, ostensibly so that he could have more time to prepare his "defence". Father Kolvenbach arranged for an initial three-month leave of absence. But Father Dupuis never returned.

Liberal clerics leapt to his defence. Cardinal Franz König, the retired primate of Austria, said that the Congregation's investigation was jeopardising the dialogue on religious pluralism that had been encouraged by Pope John Paul; its approach, he wrote, was "reminiscent of colonialism, and smacks of arrogance".

It took almost three years for the Pope's watchdogs to reach their conclusions. On February 26 2001, L'Osservatore Romano, the Vatican's newspaper, published a notice saying merely that the book contained certain "ambiguities". It did not, however, accuse Father Dupuis of doctrinal or theological error.

He felt he had been vindicated, but later told friends he thought that his every word was being scrutinised by the Congregation and that its officials were exerting pressure on his superiors to keep him quiet.

In 2002, he published Christianity And The Religions: From Confrontation To Dialogue. Several other of his works were awaiting approval at the time of his death and they remain unpublished.

Jacques Dupuis was born at Huppaye in Belgium. After entering the Jesuit order as a novice in 1941, he decided that he wanted to be a missionary in India.

In 1949, he landed in Bombay en route to Kolkata. Three years later, he began to study theology at St Mary's College in Kurseong on the slopes of the Himalayas and was ordained as a priest there in 1954. After further studies, he was sent to the Gregorian University in Rome, where he obtained a doctorate in 1959.

He returned to St Mary's as a teacher. When the theological faculty was transferred to New Delhi in 1971, Father Dupuis made the 1,250-mile journey on a motorcycle. Thereafter, he became the main theological adviser to the Roman Catholic bishops' conference of India.

He was chief editor of the theological journal Vidyajyoti from 1977 to 1984 ; during that time, he and Father Josef Neuer produced The Christian Faith In The Doctrinal Documents Of The Catholic Church.

His work in India ended in 1984, when the then head of the Jesuits sent him back to the Gregorian. In 1985, he was made an adviser to the Vatican's Pontifical Council for Inter-religious Dialogue.

In an interview with the Roman Catholic Asian news agency, Ucan, in 2003, he was asked how he thought Christ would judge his work.

"I can only hope", he replied, "that his evaluation of it will be more positive than has been that of some censors and, alas, of the Church's central doctrinal authority."