NEW ORLEANS, SEPT. 12 -- Pope John Paul II, asserting that "the Gospel should purify culture," called tonight for greater ecclesiastical control over the nation's 232 Roman Catholic colleges and universities.

"There is an intimate relationship between the Catholic university and the teaching office of the church," he told Catholic educators here. "The bishops . . . should be seen not as external agents but as participants in . . . the encounter between faith and science and between revealed truth and culture."

The pope's policy statement on Catholic education came at the end of a long, exhausting day here in which he emotionally embraced his church's black minority, was treated by Catholic youths to a small version of a Mardi Gras parade and, in his second rainy Mass, preached on the sanctity of marriage and tragedy of divorce.

His remarks on education are expected to heighten Catholic educators' anxieties over a proposed Vatican document that they say could drastically restructure Catholic colleges and universities and conceivably force some out of business.

School administrators have charged that the proposal, the first draft of which was quietly circulated a year ago, would involve ecclesiastical leaders in running Catholic colleges and universities in ways that would threaten academic freedom.

They also said that increased church controls could spell an end to U.S. government aid to Catholic schools and colleges. In his statement here, the pope did not mention the proposal, which has been returned to the Vatican for revision -- if not for burial, as American educators recommended almost unanimously.

Instead, he urged Catholic institutions to be generous in funding theological research but warned that the fruits of such research "must ultimately be tested and validated by the magisterium" -- the pope and bishops of the church.

Many Catholic theologians hold that if the church is to survive, traditional teachings must be tested continually against the experiences of the faithful in their daily lives. When there is an enormous gap between teachings and experience -- as there is today concerning birth control -- they contend the teachings must be reconsidered.

That approach last year cost the Rev. Charles E. Curran his job at the Catholic University of America in Washington and his authority to teach Catholic theology.

As the pontiff has done repeatedly on this second U.S. tour, he acknowledged the diverse pressures of modern American life. "But pluralism does not exist for its own sake," he said.

"It is directed to the fullness of truth. In the academic context, the respect for persons which pluralism rightly envisions does not justify the view that ultimate questions about human life and destiny have no final answers or that all beliefs are of equal value."

The Gospel, he said, "should purify culture, uplift it and orient it to the service of what is authentically human. Humanity's very survival may depend on it."

He urged colleges to promote spiritual introspection "as an antidote to intellectual and moral relativism. But what is required even more is fidelity to the word of God."

Speaking of "my own university experience" -- he taught philosophy in Poland before becoming a bishop -- the pope urged college administrators to attend to "the religious and moral education of students and . . . introduce {them} to a powerful experience of community and to a very serious involvement in social concerns."

"Here in the Catholic university centers of this nation," he said, "must be drawn up the blueprints for the reform of attitudes and structures that will influence the whole dynamic of peace and justice in the world."

The pope's trenchant message on higher education ended, well after dark, a day that began shortly after 8 a.m. with an official welcome at St. Louis Cathedral and a parade to the Superdome, where he met with black Catholics and later with Catholic elementary and secondary school educators.

He gave high marks and encouragement to parochial school educators, including "the thousands of lay people who have come forward as administrators and teachers." In an oblique reference to traditionally low parochial-school salaries, he said, "For a Catholic educator, the church should not be looked upon merely as an employer . . . . It is our privilege to share" in the mission of education.

Then he braced for a dose of New Orleans hospitality from 40,000 of the city's youngsters.

To the rock strains of a heavy-metal band headed by seminarian Tom Franzak of California, he was driven into the cavernous sports arena in his now-familiar white, bubbled and bullet-proofed "popemobile" as the electronic scoreboards lit up with a "Welcome Pope John Paul II" message between ads for Budweiser beer and Mitsubishi appliances.

Led by the snappy St. Augustine High School Marching 100 Band of New Orleans, a much-abbreviated Mardi Gras parade with floats and clowns was conducted before the pope's obviously amused eye. At the end, when Louisiana's youths presented him with a plumed Mardi Gras mask, he struggled bravely, but in vain, to tie it behind his white-capped head.

In addressing his youthful audience, the pope returned to his theme, already much used in the first three days of his 10-day American tour, of the dangers of unbridled freedom.

"You young people are proud to live in a free country, and you should be grateful to God for your freedom," he said from a large stage in the end zone. "But even though you can come and go as you like, and do what you want, you are not really free if you are living under the power of error and falsehood, or deceit or sin."

Speaking forcefully, with a sense of emphasis and drama, the pope said, "Dear young people: The word of Jesus and his truth and his promises of fulfillment and life are the church's response to the culture of death, to the onslaughts of doubt and the cancer of despair."

"Do not believe anyone who contradicts Jesus or his message which is transmitted to you by the church," he said, also urging them not to succumb to selfishness "that destroys the meaning of life, the meaning of love; it reduces the human person to a subhuman level."

As he has every time he meets young people in his travels, the pope sought to impress them with their responsibility for the future of mankind and the power that they hold over the state of the world they live in.

"What is needed today is a solidarity between all the young people of the world -- a solidarity especially with the poor and all those in need," he said, to applause. "You young people must change society by your lives of justice and fraternal love. It is not just a question of your own country, but of the whole world."

The pope's morning was warm and dry, but his afternoon was cold and wet.

The public Mass at the University of New Orleans was visited by bad weather -- high winds and rain, but without the lightning that shortened his Mass Friday in Miami. Here, he was able to finish the event, which drew an estimated 200,000 Louisiana worshipers and featured communion music by some of the city's finest jazz musicians, including clarinetist Pete Fountain.

His homily focused on the relationship of justice, love and forgiveness. Human justice, he said, "is often governed by hatred and revenge," and when that is so, without a balance of love and forgiveness, "the rigorous application of the law can sometimes be the height of injustice."

He applied the same approach to marriage -- and divorce, which church teachings condemn. "If couples cannot forgive with the tenderness and sensitivity that mercy brings," he said, "then they will inevitably begin to see their relationship only in terms of justice, of what is mine and what is yours -- emotionally, spiritually and materially -- and in terms of real or perceived injustices. This can lead to estrangement and divorce and often develops into a bitter dispute about property and, more tragically, about children."

And he also applied it to economic imbalances: "A case with special urgency today is the international world debt," he said. Many developing countries are heavily in debt to industrialized nations, and find it increasingly hard to repay their loans. "Blind justice alone cannot solve this problem in an ethical way that promotes the human good of all parties," he said.

Many of the Catholics the pope will encounter Sunday, when he leaves New Orleans for a huge outdoor Mass in San Antonio, are from the Central American countries to which he referred.

He will bring a similar message, but his entourage is hoping for better weather in Texas, where high winds Friday blew down the altar built for his visit.