The man in cream white robes and skullcap stands up in the matching white Toyota Jeep as it moves through the throngs in St. Peter's Square at a slow crawl in the hot Roman afternoon sun.

The jeep stops every so often so that the figure can lean down to kiss an infant, holding it a long moment, enough for any proud parent to take a good picture.

Itis John Paul II, the pope who has become a media star and who has held Rome enthralled since his election eight months ago.

Roman cynics have been waiting for the public to tire of the spectacle of the new style of the Polish Pope, Il Papa Polacco, as the Italians call the first foreign pontiff in five centuries. Instead, the crowds keep growing as the faithful respond to this well-built, athletic, spiritual leader who encourages contact with the masses instead of giving the impression of fleeing from them as did his predecessors.

Some church intellectuals turn up their noses at the pope's refusal to spurn media stardom. That aura of glamour should be enhanced many times over during the pope's much heralded trip to his native land that begins Saturday.

Yet this stardom is the essential change that Karol Wojtyla, the 59-year-old former cardinal-archbishop of Krakow, has brought to the Vatican.

The result is that the Roman Catholic Church, which had been giving an impression of faltering in the world, now projects a new image of vigor and self-confidence.

The pope's evident fascination with the gadgetry and gimmickry that he has found in the West - the helicopters and electronics, the news media that will send out his every word - have led to no concessions to modernism when it comes to church doctrine and tradition. Quite the contrary.

Traditionalists, who were very upset by the new directions the church took with the Second Vatican Council under Popes John XXIII and Paul VI, have been reasured by the new pope's stern orthodoxy on the celibacy of priests, divorce, contraception and abortion.

Liberals express increasing uneasiness as the pope begins to define his doctrinal positions. While the pope expresses continued support for unity with other Christian churches, he has begun to close off many of the new avenues of Catholic thought that were bringing Catholic theologians closer to their Protestant colleagues.

Communists are also uneasy, without being able to pinpoint exactly what bothers them. The Italian Communists, who are the most directly concerned, say they are pleased because the pope seems definitely to have taken the church out of Italian politics and because he has reaffirmed the search for good relations with the Communist states of Eastern Europe.

Gerardo Chiarmonte, the Italian Communist Party's second most important leader, said in an interview, "From our viewpoint, the pope hasn't been negative, strictly speaking, but at a deeper level, this rallying of the Catholic masses can prove to be very negative as far as we are concerned.'

John Paul's attraction is so strong that whole villages as a group, town communists and socialists included, hire buses to come see him.

The most compelling argument inside the church for going with the times has been the declining number of priests around the world. About 32,000 have left the priesthood, most often to get married, since 1964. Few young men are entering seminaries.

To meet this crisis, church modernists have proposed letting priests marry and the recruitment of married men as priests. The pope's answer has been a ringing no.

In a 35-page letter to priests in April, the pope rejected all the arguments for abandoning celibacy and called on them to keep "one's word to Christ and the church." It may sometimes seem, the pope said, that the faithful want their priests to be "like them," but this is an illusion.

"Those who call for the secularization of the priestly life and applaud its various manifestations will undoubtedly abandon us when we succumb to temptation," wrote John Paul II.

To those tempted to quit the religious life, he urged prayer and an effort to be "converted anew every day."

The immediate reaction of many churchmen concerned about the crisis of vocations was that the pope, who comes from one of the rare countries where there is no shortage of candidates for the priesthood, was demonstrating his provincialism by not considering the recruiting problem in the rest of the world.

His answer seems to be that the power of his own vigorous example can show how to inspire renewed dedication, even in countries where the church does not play the special role it does in Poland of representing the people against the state.

A price has been exacted for the pope's stardom.

There is the insatiable curiosity that turns relatively serious political publications into movie fan mags. This week, instead of doing a cover story on the Italian elections a few days away, the newsweekly Panorama ran a cover on "Karol and Halina Exclusive: The True Story of the Pope's Young Love."

It was nothing racier than an account of how Karol at 14, got up the courage to ask an attractive 12-year-old for permission to carry her school-books and that he used to spend a lot of time holding hands and taking walks with her in his early teens.

She is now the 57-year-old first lady of the Krakow theater and has had an unhappy marriage. A daughter of that marriage, now 33, was the first baby Wojtyla baptized as a young priest.

There is the inconvenience caused by the crowds that come to see him. He has had to revise the schedule for his weekly audience to accommodate the thousands who come to see him.

There is the inevitability that every little word the pope utters will be blown out of proportion. When he said at his audience this week that he hoped people would vote in the forthcoming Italian national and European Parliament elections "with a sense of responsibility and of maturity inspired by the profound dictates of one's own conscience," some reporters in Rome immediately jumped on that as a statement of support for the ruling Christian Democratic Party in Italy.

That interpretation completely ignored the thrust of recent Vatican actions attempting to disengage itself from Italian politics. As the Rev. Bartolomeo Sorge, a Jesuit priest who edits Civilita Cattolica, the nearest thing the Vatican has to an official theoretical journal, recently said, the Christian Democrats are not "the party of the Catholics" but a party of Catholics.

Catholic liberals feel that the pope goes out of his way to hold the door open for the rebels against the reforms made by the Vatican Council. In Western Europe, the rebels led by Msgr. Marcel Lefebvre are almost invariably associated with far right politics.

The pope's willingness to receive Lefebvre seems to be more related to a Lyndon Johnson-style "let-us-reason-together" approach than to any personal sympathy for Lefebvre's position.

Many church liberals were particularly upset by John Paul's speech to the Latin American bishops' conference in Puebla, Mexico, rejecting the idea of Jesus Christ as a revolutionary. The view of Jesus as "the subversive from Nazareth," said the pope, was the false interpretation by His prosecutors.

This view of Christ as a spiritual leader eschewing politics may explian John Paul's determination to get the church out of entanglement in Italian politics.

For the pope from Poland, relations with Eastern Europe have been the litmus test of his diplomacy and, so far, he is generally seen to have passed with flying colors. As one liberal, the Rev. Giovanni Baget-Bozzo of Genoa, put it, "John Paul II is like a living ostpolitik. He brings the two halves of Europe together in his person."

There is also general approval for the pope's key appointment to date, of Cardinal Agostino Casaroli as secretary of state. He was Pope Paul VI's "foreign minister" in charge of the ostpolitik.

"The Casareli appointment was so perfect that it seemed inevitable," said one close Vatican observer. "The pope himself reassurs the churches of Eastern Europe, and Casaroli reassures the governments."

Yet, all the stress on relations with Eastern Europe, and the appointment of an unusually large number of East Europeans at the Vatican, leaves the church liberals who are concerned about relations with the Third World perplexed.

They express worry that the pope is unfamiliar with the problems of Asia and Africa and has little grasp of a movement that may be replacing communism as the church's biggest long term threat - Islam.

The pope speaks often of his attachment to the Vatican Council reforms and to Paul VI, the man who brought them to fruition. Yet, there seems to be no doubt that the new pope considers that it is time for the church to stop and digest the long string of reforms.

The key reform about which church liberals worry is collegiality, the idea that the pope rules the church in conjunction with the bishops. Even those who insist that it is too early to say that John Paul has turned his back on collegiality admit that the force of his personality is so overwhelming that any notion of collective leadership seems bound to suffer.

A French priest compared John Paul to Billy Graham, saying that the people who come to see the pope in St. Peter's Square seem to come more to partake of his presence than to listen to anything he actually says.

"When you look at the other leaders in the world today," said the priest, "you understand the hunger for a father figure. He comes to be with his people, but more to be applauded by them than to be in communion with them." CAPTION: Picture, Pope John Paul II hugs a little girl during his visit to Mexico in January. UPI