SAN ANTONIO -- The pope does not come to town every day, not even John Paul II, the traveling pontiff, who in eight years has visited more than 60 countries on 35 pastoral tours. On Saturday, the fourth day of his second U.S. sojourn, he will grace this largely Hispanic Catholic city in south Texas for the first time. Among those preparing for his arrival are three carpenters named Al Lopez, Joe Collazo and Eddie Berones.

In other American precincts, questions of doctrinal politics smolder: Why did the pope meet with Austrian President Kurt Waldheim? Why are women barred from the priesthood? How does he justify a 10-day trip that costs $93,572 an hour? Why is he unyielding in his positions on birth control, divorce and homosexuality? But in San Antonio, when they wonder whether it will be too hot for His Holiness, the question is literal.

Here, where the pope's status is such that Mayor Henry G. Cisneros named his infant son John Paul, there is more concern about the temperature at the Mass site than the intensity of the religious debate.

The three carpenters answer theological questions with callused THE PAPAL VISIT First of Three Articles hands. They are building an altar for the pope, who at noon next Sunday is expected to celebrate Mass with 500,000 worshipers. The altar rises step by step on the city's western rim, on a rolling, treeless field that has browned under the blinding late summer sun, and with every nail they pound, Lopez, Collazo and Berones feel a measure of humility, repentance and pride.

"Not too many people get to say they helped the pope when he was here," said Collazo, escaping 99-degree noonday temperatures in the cool, dark shadows of the wood-covered scaffolding. "For the rest of my life, I'll be able to say, 'I did a little bit of work for the pope. I helped make the pope comfortable.' If you don't appreciate that, you don't understand what life is about."

Much of the land that Pope John Paul II will see during his return visit to America, which begins Thursday, is far different from his northern swing in the fall of 1979. This one, mostly along the southern arc from Miami to San Antonio to Los Angeles, is more traditional, conservative, adoring and compliant in its Roman Catholicism. Its relationship with the Vatican is less fractious than that in the rest of North America and more like that in other parts of the world, especially Latin America. It makes sense, since the southern and southwestern Catholic church was born into Latin dominance and is returning to it as the new immigrant church.

One way to appreciate this: When the pope lands in Miami, he will be in a diocese that began under the religious jurisdiction of Santiago, Cuba. New Orleans, his third stop, was originally part of the diocese of Quebec. San Antonio was once part of the diocese of Monterrey, Mexico, and Catholics in Phoenix, the next stop, long ago belonged to the Mexican diocese of Guadalajara.

In Miami, where no priest may be ordained unless he speaks Spanish and English, the percentage of Hispanics in the Catholic diocese has grown from 10 percent in 1959, when the massive Cuban immigration began, to 62 percent. Los Angeles, the largest Catholic diocese in the country, by some calculations has more people of Mexican descent than any city except Mexico City, and 92 percent of them are Catholic.

Of the nation's 53 million Catholics, 4 million live in Texas. Five of every eight Texas Catholics are Hispanic, and the numbers are changing rapidly. As far north as Dallas, Bishop Thomas Tschoepe notes that transformation by saying, with slight exaggeration, that 90 percent of his funerals are Anglo and 90 percent of his baptisms are Hispanic.

What this means is that the pope and his audiences will have a closer fit than might be expected in a country where, to a large degree, Catholicism has become more a personal religion than an ethnic and cultural bond. His blend of social conservatism and economic socialism is a reverse of modern American trend, but less so among Hispanics and other minority Catholics he will meet with during this trip. These include many blacks, Asians and Native Americans to whom the daily struggle for work, shelter and human dignity is the preeminent concern.

"This pope speaks the language of the minorities," said the Rev. Curtis Guillory, vicar of 100,000 black Catholics in New Orleans. "In one of his pastoral letters, Laborem Exercens, he said that one way the dignity of the human person can be affirmed is through employment. That had a special meaning to blacks in America who comprise the highest percentage of the unemployed."

A recent poll of Hispanic Catholics by the Mexican-American Cultural Center found that to them, economic survival far outweighed any doctrinal issues. "On his last trip, his message was drowned out by the personal issues of the white middle class," Stephen Sander, a theologian at Notre Dame Seminary, said at a recent seminar in New Orleans.

"Most Americans only hear his teachings on sexuality, birth control and the place of women in the church, but the real crisis for the pope is socioeconomic injustice. The leading questions for American business leaders are: 'Is it feasible? Can we make money?' But the pope calls on business to ask: 'What is the consequence of this policy for the worker?' He is more concerned with labor than with capital. And he asks us to see society from the eyes of those at the bottom."

Many of those at the bottom consider his decision to visit them a profound statement in itself. The Rev. Anthony Monteleone, pastor of Our Lady of Guadalupe Church in the heart of San Antonio's working-class Hispanic west side, put it this way: "When Pope John Paul II visits this church, it will be an affirmation to these people of their struggles, their traditions, their lives, their faith and their very language."The Vatican's Laboratory

That is not to say that the 264th successor to the See of St. Peter is pulling an end run on this trip, that he would or could avoid other controversies. Bernard Swain, a theology professor at Harvard, once said that the Vatican views the United States as its laboratory for learning how to survive in the modern, secular world. For this, the pope's second semester of American lab work, the tests will be constant despite the respectful nature of most Catholics on his route. When a pope comes to study America, the nation sits in on his class.

The tuition is high, which raises a question: Is the trip worth the cost? The total could reach $40 million, more than half of it raised by the host dioceses, and the rest coming from federal, state and local agencies -- ranging from $5.6 million from the Secret Service to $18,000 from the Florida Game and Fresh Water Fish Commission -- for protection, traffic and cleanup. Many of the dioceses have fallen short of their fund-raising goals; in San Antonio, church officials were faced with the probability of taking out a short-term loan of $800,000 to meet expenses of $2.5 million.

After reciting some of the frills -- $200,000 worth of palm tree landscaping in Miami; a small river for the mass in the Pontiac, Mich., Silverdome; a fabric replica of the Grand Canyon in Phoenix -- Sister Margaret Traxler of the National Coalition of American Nuns, said: "For all that money, think of what you could do for the homeless and hungry. The money could be far better spent if he stayed in Rome."

Her opinion is shared by many. A Gallup Poll conducted for The Detroit Free Press last month showed that 42 percent of the Catholics in that city, the last stop on the pope's tour, thought the money would be better spent on the poor.

There is also the question of whether public funds should be spent at all on this trip. The federal money is explained on the grounds that the pope is also a state official, representing Vatican City. But it is a sore point with many non-Catholics, especially in states such as Texas that are suffering economic hardships.

After Texas Gov. Bill Clements (R) agreed to spend several hundred thousand dollars for National Guard units in San Antonio, Maury Maverick Jr., a liberal columnist here, noted that the Texas Constitution prohibits such expenditures: "Where is a Texas politician who will stand up for separation of church and state? Sam Houston! Sam Houston! Where are you?"

Church officials counter that their expenses are in line with what major corporations spend on advertising campaigns, and they say his trip is unabashedly an advertisement for the church. During his 10-day blitz, John Paul II will be seen by as many as 10 million people celebrating Mass or gathered along the parade route of the Popemobile, and the traveling party will include a three-plane TWA squadron -- two L1011s and a custom-fitted 727 -- carrying the papal retinue and 315 print and broadcast journalists. More than 20,000 journalists have credentials to cover him on the ground.

In any case, it is just plain hard to keep this 67-year-old pope in the Vatican. In late January 1979, three months after Karol Cardinal Wojtyla of Poland became Pope John Paul II, he made his first overseas trip -- to Mexico -- and he has been on the move ever since. In his first two years, he logged more miles than all of his predecessors combined. Along with deepening the faith of the world's 840 million Catholics, the pope looks upon his travels as a means of strengthening himself by staying in touch with the people and of sharpening the essential method of his papacy. That method is what he calls the "sign of contradiction" -- seeking to unify while risking alienation by speaking out against the evils of the modern world.

The contradiction was evident during his first U.S. trip. While his audiences showered him with adoration, and the American news media, witnessing his charisma for the first time, portrayed him in glowing terms, his message grew stronger and starker until in Philadelphia he pounded out the church teachings that bar women from the priesthood. Then in Washington, as a National Conference of Catholic Bishops paper phrased it, "he rejected the ideology of contraception, proclaimed marriage indissoluable, condemned homosexual activity and sexual intercourse outside of marriage and called abortion an unspeakable crime."

On many of those issues, he and American Catholics differed sharply. According to a 1985 Notre Dame Study of Catholic Parish Life, a survey of 2,667 parishoners in 36 parishes, 66 percent do not believe that the church should remain strong in opposition to contraception, 64 percent think the church should liberalize its divorce position, 37 percent think women should be allowed to be priests, and 69 percent think abortion should be acceptable under extreme circumstances, such as rape or incest.

The theme of this second visit is "Unity in the Work of Service." In each city, there is a subtheme of the church's work, ranging from the priesthood in Miami to charities in San Antonio to hospitals in Phoenix. The pope seeks to have a dialogue on each of those subjects. But inevitably, there will be contradictions, some of his choosing, some not, that will shift the focus of attention. Symbolic Statements

In Miami, his first stop, even before he is welcomed by President and Nancy Reagan, he will deliver a message to American priests, whose numbers are declining (from 58,301 in 1977 to 53,382 now), whose role is in question and whose morale is on the line. They will be looking for encouragement.

Then the pope will discover a church that "deals in politics with a capital P," said the Rev. Thomas Wenski. Many in Miami's refugee community want John Paul II to make a statement against Castro's Cuba, but some diocese officials say that is unlikely because the church's relations with the Marxist island state seem to be improving.

But the central issue in Miami is likely to be his meeting with 196 Jewish leaders, and though it is billed as largely ceremonial, recent relations between the Vatican and Jews have been anything but. Modern tensions came from Pope Pius XII's failure to sound an alarm against the Holocaust and, later, the Vatican's refusal to recognize Israel. Pope John Paul II dismayed Jewish leaders in June by meeting with Waldheim, who served during World War II with German army units implicated in deporting Jews in Greece.

The pope's advisers said the Waldheim meeting was in no way an endorsement; the pope even met Mehmet Ali Agca, the man who tried to assassinate him in 1981. Vatican talks last week between the pope and Jewish leaders went a long way toward easing tensions, although no substantive changes in diplomatic policy were made.

From Miami, the pope travels Friday to South Carolina, where the number of Catholics is so small -- less than 2 percent of the population -- that the entire state belongs to one diocese. The main event is an interfaith prayer service in Columbia that will be attended by many of the nation's Christian leaders. Mainline Christian churches and the Vatican agree more than they disagree on social and doctrinal issues, differing chiefly on moral ones. But Episcopal Presiding Bishop Edmond Browning and many of his colleagues said they prefer not to confront the pope, but to embrace him as a symbol of world peace.

Since Vatican II in 1964, Catholic leaders have been moving toward reconciliation with non-Catholic Christians, and John Paul II has encouraged that movement, although he has not shied away from his method of contradiction. In 1984, for example, he wrote a letter to Archbishop Runcie of Canterbury, primate of the Anglican community, that ordinations of women by some Anglican churches had become "an increasingly serious obstacle" to unity.

In New Orleans, the pope will hold a historic meeting with 1,800 national black Catholic leaders. Although blacks are 2.5 percent of the country's Catholics, according to offficial church estimates, in New Orleans the figure is over 20 percent, a tradition that dates to French Catholic slave owners who baptized their black slaves and placed them in the balcony during Sunday Mass.

Black Catholicism has increased in recent years, in part because the church finally allowed church choirs. Twenty years ago, there were no gospel choirs in the Catholic churches of New Orleans; now there are 40. Father Curtis Guillory and other black church leaders say the next step for minorities must come in the priesthood. Only .04 percent of the priests are black. Hispanics are similarly underrepresented. Although they comprise as much as 30 percent of American Catholics, by church estimates, they have 3 percent of the priests.

"If the church is going to be credible, it has to be reflective of all the minorities that belong to the church," Guillory said. "We hope the holy father will say something that will give vision to this." The Heat and Traffic

By New Orleans, if not sooner, the physical difficulties of the pope's tour will be evident. For an outdoor Mass at the University of New Orleans, the diocese is expecting 277,000 celebrants, and only two roads lead to the site. Echoing the sentiments of traffic planners in most cities along the tour, John Exnicios lamented: "There's no use kidding ourselves. There are going to be unusual and extraordinary traffic delays." But the weather will be even trickier.

In many of the tour cities, the prospect of hundreds of thousands of people standing for hours in the heat and humidity of early September has sounded alarms. The average high in Miami for those dates is 88, for New Orleans 88, for San Antonio 90 and for Phoenix 95. Church officials have been forced to make some unusual statements in efforts to ease the anxiety. In New Orleans, Archbishop Philip Hanan noted that medical facilities at the Mass site would be so good that "if you feel like you're going to have a heart attack, this is the place to come."

The hottest weather debate has raged in San Antonio, where the region's health director, Katherine Rathbun, resigned over fears that medical and water facilities would be inadequate for the 500,000 people expected at the Mass. Her final words of advice were: "Don't go. Stay home. People are going to die!"

But the diocese refused to limit the size of the crowd, which might include as many as 125,000 pilgrims from Mexico. At a news conference two weeks ago, Dr. Fernando Guerra, who replaced Rathbun, said they were prepared to handle a 3 percent injury rate -- 15,000 people -- mostly for heat-related problems; that 800,000 gallons of water will be available in 170 outlets; that the young, sick and old should stay home; that everyone should bring suntan lotion, and that to acclimatize themselves to the heat, Mass-goers should turn off their home air conditioners five to seven days before the event.

Hospitals and medicine will be equally timely topics when the pope reaches Phoenix, where he will meet with Catholic health care administrators and is expected to stress the church's position on medical ethics and the sacredness of life. But the most colorful event there will be John Paul II's appearance at the Tekawitha Conference, a meeting of 16,000 American Indian Catholics who will gather in honor of a 17th century Mohawk maiden beatified by the pope seven years ago.

Of the 1.5 million Native Americans in the United States, about 285,000 are Catholic, although most of them also practice their traditional religious beliefs. Bishop John Pelotte of Gallup, N.M., the first Indian Catholic bishop, said the meeting would be a step toward reconciliation of a relationship that began when priests accompanied the conquering Spanish. "We've come a long way since then," Pelotte said.

In Los Angeles, where 5 percent of American Catholics live, the pope will celebrate Mass at the Coliseum and Dodger Stadium and meet with entertainment industry executives at Universal Studios. No one seems quite sure what is going to happen at that meeting, although the pope, a published poet and playwright, has strong feelings about Hollywood. In a 1984 speech he said that too often, "freedom of expression is confused with license" and urged entertainers not to "corrupt society, especially young people, by complacent and insistent repetition of evil, of violence . . . ."

(At his next stop, in Monterey, Calif., where he will celebrate mass at a racetrack and talk about the importance of farming, the pope will be greeted by Mr. Magnum Force himself, actor and Carmel Mayor Clint Eastwood.)

One of the Los Angeles themes will be ethnic diversity, and 15 to 20 languages will be used at the Dodger Stadium Mass. U.S. bishops will attend as a group, and there will be subtle reminders of their differences with their leader. Women will read the scriptures, a message underscored by Archbishop Roger Mahony, who in mid-August issued a strong pastoral letter saying that women should be allowed leadership positions and expressed concern over sexist language in the liturgy.

Although gay-rights activists are expected to be among those protesting and holding silent vigils outside the chanceries in every city, they will get their one chance to speak with the pope in San Francisco. When he arrives at Mission Dolores, the welcoming ceremony will include 100 AIDS patients, most of them homosexual men, and inside he will have an audience with six parishoners, including John Revick, who is gay and heads the church liturgy committee.

Revick said his first reaction was, "I don't want to meet the man," but that later he decided, "I see this as my way to forgive the church, to forgive the pope."

For his final stop, the pope will fly north Sept. 18 to Detroit, where he will visit 100,000 Poles in the enclave of Hamtramck and speak about social justice, the most important item on his personal agenda. During his first visit to America, the pope delivered a powerful homily at Battery Park in New York about the need to "break open the hopeless cycles of poverty and ignorance that are still the lot of too many of our brothers and sisters; the hopeless cycles of prejudices that linger despite enormous progress toward effective equality in education and employment; the cycles of despair in which are imprisoned all those that lack decent food, shelter or employment."

As he leaves, American Catholics will be looking for indications that he has heard their concerns -- that he has heard "a few things from some people extemporaneously, not just let himself be informed, conditioned and prepared by those nearest him," said Sister Fara Impastato, a theology instructor at Loyola University in New Orleans. "The holy father needs to hear from ordinary people the things that might make him ask himself, 'I wonder why this woman is so upset? What is she really saying?' "

Pope John Paul II is likely to gauge the ultimate success of his trip by a different standard -- the extent to which American Catholics accept his challenge to extend their faith beyond their personal concerns into their communities.