As protests against the Vatican's disciplining of theologian Hans Kung mounted yesterday, the Swiss-born scholar defied the church order banning him from teaching theology and vowed to retain his professorship at the University of Tubingen in West Germany.

"I hope to overcome, finally," he said last night in a telephone interview, but he acknowledged that "it will be very difficult" to force the Vatican to reverse its judgement against him.

On Monday, the Vatican's Congregation for the Doctrine of the Faith ruled that Kung, the best known theologian in the church today, "can no longer be considered a Catholic theologian nor function as such in a teaching role" because some of his writings have "departed from the integral truth of the Catholic faith."

The ruling, which stunned church scholars around the world, is the latest development in what appears to be a crackdown by the church under Pope John Paul II on progressive theological scholarship.

Reached at his home in Tubingen after a tumultuous day yesterday, Kung said he would fight to have the judgement against him withdrawn. Such an action might be possible, he said, "if there are enough repercussions against it by the public."

At the German university yesterday, about 2,000 students, faculty members and townspeople jammed a lecture hall and a nearby auditorium, with sound piped in for the overflow to hear his 90-minute lecture. Later, he spoke appreciatively of their support for his pledge to stay on at the university. Afterward they staged a demonstration for him downtown in the university city, he said.

He said also that sudents of the universities of Fribourg and Lucerne in his native Switzerland had planned demonstrations in his behalf, despite an appeal by the Swiss hierarchy to respect the Vatican decision.

In Tubingen, a group of scholastics and churchmen formed a "Committee for Human and Christian Rights in the Church," Kung said, headed by Prof. Walter Jens of Tubingen, who also heads the West German branch of PEN, the international writers club.

In the United States, an ad hoc group including the Rev. Charles Curran of Catholic University and the Rev. David W. Tracy of the University of Chicago, obtained the signatures of more than 70 well-known Catholic theologians to a statement asserting that whether or not they agree with Kung's views, they "publicly affirm our recognition that Hans Kung is indeed a Roman Catholic theologian."

Kung, who said he "had no warning" of the pending Vatican action against him and was "skiing in the Arlberg" in the Austrian Alps when he was notified of the Vatican's decision, was bitter about its timing.

"Just before Christmas!" he exclaimed. "How is that possible for a religion of love, whose message is love?"

The action against him, he said, "has to be seen in the light of the Schillebeeckx trial and the case of the Dutch church." The Rev. Edward Schillebeeckx, a liberal theologian, was summoned to the Vatrican for questioning last week. Bishops of the Dutch church, whose hierarchy a decade ago was one of the most progressive in the world but is currently badly divided have been called to Rome next month by the pope himself for a session.

The World Council of Churches, which has been in conversation with and conducts some cooperative endeavors with the Catholic Church, said yesterday that the Kung banning could harm further talks. Kung got in trouble in part because of his questioning of papal infallibility and authority in the church. WCC head Philip Potter called these issues "the most sensitive point in ecumenical theological discussions."

Dean Wolfgang Bartholomaeous and eight other faculty members of the University of Tubingen said yesterday in a statement of support for Kung: "We see heavy damage for the believeability of the church in today's society and for the freedom of theology in research and teaching."