More than 100 leading Jesuits from around the globe began a week-long meeting here today that many see as a showdown with Pope John Paul II, who has expressed concern over the progressive, activist orientation of segments of the 442-year-old Roman Catholic order once known as "the soldiers of the pope."

Once the watchdog of Roman Catholic tradition, the Jesuits have been in the forefront of theological revisionism since the second Vatican Council of the early 1960s. Although they are divided, Jesuits have been among the most open-minded Catholic clerics on celibacy, birth control and the ordination of women.

In some parts of the world they have played an increasing part in attacks on social and political injustice. At times, particularly in Latin America, individual Jesuit priests have adopted Marxism, espoused revolutionary movements and even backed guerrilla forces.

The pope is known to believe some Jesuits have gone too far. He has been sharply critical of them for what he called "secularizing tendencies," a lack of austerity and discipline, straying from doctrinal orthodoxy, and in some places excessive political and social involvement.

For the current session, running into next week, 86 Jesuit provincials and over a dozen assistants will meet in a secluded 18th-century villa outside Rome to discuss the future of the 27,000-member Society of Jesus. On Saturday, the pontiff is expected to spell out his views on the Jesuits for the first time since he openly deplored what he termed "regrettable shortcomings" of some members of the order 2 1/2 years ago.

Last fall the pope intervened in Jesuit affairs in an unprecedented manner when he installed the Rev. Paolo Dezza, 80, a respected Jesuit scholar, as his special delegate to the Society of Jesus. Dezza, who chairs this week's meeting, thus effectively displaced both the order's ailing Spanish superior general, the Rev. Pedro Arrupe, and the latter's hand-picked temporary vicar general, American Jesuit Vincent O'Keefe.

The official purpose of this week's meeting, according to a Jesuit statement issued yesterday, is "to relay to the whole society...the pope's wishes regarding the society and to ponder how the society might best accede to them."

The pope's demands, expected to hinge on a need for greater spirituality and increased emphasis on theology and pastoral functions, could affect the shape of Jesuit activity.

Vatican observers and liberal Catholics worried about John Paul's tendency to favor doctrinal rigidity and political conservatism will also be watching developments closely to see if this analysis of his 3 1/2-year papacy is corroborated.

For example, progressive Catholics, including many Jesuits, complain that although the pope has spoken eloquently in defense of the church in Poland, he has been slow to back liberal churchmen in human-rights disputes with Latin American governments.

The order was established by Ignatius Loyola in 1540 largely as an intellectual force to combat the growth of Protestantism. Over the centuries the Jesuits developed an unchallenged position within the church as theologians, thinkers and educators.

Today their members, more than 5,000 of them Americans, work in more than 100 countries, frequently as missionaries and schoolteachers. Their current intellectual influence in Rome alone can be gauged from the fact that they run the prestigious Gregorian University, the Vatican radio and the influential Civilta' Cattolica monthly.

In 1979, a year after John Paul's election, he told an international Jesuit meeting here the society was "causing confusion among Christians and anxieties to the church and also personally to the pope who speaks to you." At the time he asked Arrupe--the current "black pope," as as the black-robed Jesuit leader has always been called--to convince the Jesuits to remedy their shortcomings. Six months later, John Paul ordered Arrupe to forbid American Jesuit Robert Drinan from seeking reelection to the U.S. House of Representatives.

Although pope Paul VI was also reported to be concerned about trends among the Jesuits, he declined to intervene. But given the present pope's oft-expressed conviction that a priest's function is religious rather than political, a clash was probably just a question of time.

Alone among Roman Catholic orders, senior Jesuits take a special vow of obedience and loyalty to the pope, and are therefore expected to accept his dictates, including his choice of a successor to Arrupe if the pope specifies a candidate.

A new superior general would be elected at a general congregation, the date for which has yet to be set. But when the pope appointed Giuseppe Pittau, 52, as Dezza's assistant last October, he gave the impression that the little-known former provincial of Japan was the leading contender.

A Jesuit here says most of 5,000 letters from Jesuits indicate an inclination to bow to the pope's will.