One of the most controversial figures in the Roman Catholic Church, theologian Hans Kung, warned an audience here against getting so hung up in controversies that the essential of Christianity, Jesus Christ himself, becomes obscured.

"The central question" for the Christian church in the midst of myriad changes in both the world and the chrch "is to know what really is the central question . . . What is there that really must remain?" Dr. Kung said in the first of three lectures at Georgetown University here.

"The essence of Christianity . . . the distinctive Christian reality is not an idea, not a principle or an axiom but the distinctive Christian reality is simply Jesus Christ Himself," Dr. Kung said in answer to the question.

Dr. Kung, whose book, "On Being a Christian," is one of the few theological works in recent years to make best-seller lists both here and in Germany where it was originally published, was sponsored in his appearance for these lectures here by the Kennedy Institute for the Study of Human Reproduction and Bioethics.

The lecturship itself was named for Rose KennedY, "in acknowledgement of the simple fact that some people actually manage to live Christianity," said the institute director, Dr. Andre E. Hellegers, in introducing Dr. Kung at the first lecture. Several members of the Kennedy family, including Sen. and Mrs. Ted Kennedy, were in the audience of several hundred persons.

Dr. Kung began his lecture by citing a list of "positive changes" in the Catholic Church in the 15 years since the opening of the Second Vatican Council:

A "world encompassing movement toward ecumenical agreement."

Relations between Christians and Jews, which he called "a particularly sad chapter" in the history of the Church, have been "considerably improved."

Revisions of the liturgy to make it "more intelligible."

A decline in "popular piety" and the growth of devotional practices "more inspired by the central truth of the faith."

Structures of the Church have become "slowly more democratic . . . in some centers more, in some, less."

"The Christian church is more alert to pressing social needs around the world" such as questions of human rights, poverty and problems of the third world.

A "new spirit of freedom of thought" has "become a reality in the Church."

The theologian also cited a list of what he termed "changes for the worse" experienced by the Catholic Church in the past 15 years.

Christian churches, he pointed out, have experienced the same "tremendous upheaval of the general society." But problems unique to the Church, he said, include the "massive departure from the ministry of tens of thousands of priests, a weakening of the ecclesiastical spirit, "and crisis in certain [WORD ILLEGIBLE] church institutions such as schools and publishing houses.

Dr. Kung also complained of a "want of spiritual leadership in Rome." He explained that despite his battles with the Vatican, he was not anti-authority. "I think we need an inspiring international authority in all levels," he said.

The Swiss born theologian who teaches at the University of Tubingen in West Germany, has gained a reputation as an opponent of papal authority for his teaching and published works challenging the doctrine of papal infallibility. He also has defied several Vatican orders to cease disseminating his ideas.

Dr. Kung said there is "a dangerous gulf between bishops and priests" in the Church and a "loss of credibility by Pope Paul VI.

The previous pontiff, Pope John XXIII, Dr. Kung said, enjoyed "the greatest credibility in 2,000 years.Now it (credibility) is so slow that it is impossible to explain how it came to be so."

The theologian said his criticism was directed at the "policy and state of the Church, not at Pope Paul personally." He added that the recent Vatican document declaring that women could not become priests because they did not resemble Christ was "only symptomatic" of the Vatican's credibility problem.

He added that "women should have equal rights. I think the present documet (on women) has to be reconsidered."

He also called for a greater role and recognition and role of the laity, for priests to have the option to marry, and for questions of birth control to "be decided by parents in the light of their consciences."

He also said the Church should "not leave appointment of bishops to the secret cabal of Vatican bureaucrats and friends if we want to get better leadership." Instead, he said, bishops should be chosen by more representative groups, such as diocesan councils.

He added that popes, who now are chosen by secret election by the College of Cardinals, "should be elected by a body of priests and lay people truly representative of the people."