Argentina's traditionally conservative Roman Catholic Church, after years of tacitly supporting military rule and restraining its public criticism of alleged human rights violations, in recent months has changed course and begun to call for a return to democracy and "the rule of law."

The church's new stance, described by Catholic scholars here as the strongest support for civilian democracy in the modern history of the Argentine church, has included denunciations of "illegitimate repression" by the armed forces. In particular, the hierarchy has assailed the military and called for "the truth" about the thousands of missing persons and cases of prolonged imprisonment that have been charged to the government.

The church also has mounted strong criticism of the lowered standards of living that have accompanied the government's conservative economic programs.

The hierarchy has underlined these views with a series of well-publicized actions ranging from pastoral letters and meetings with leaders of civilian political parties to a Christmas Eve trip by the papal representative here to a prison holding hundreds of political detainees.

Latin America has the largest concentration of Catholics in the world, and in many Latin countries, including Argentina, where 90 percent of the 26 million population practice Catholicism, it is the state religion. Long supportive of traditional authoritarian governments, the Latin church in the past two decades has become increasingly active on behalf of human rights and social issues.

But while the Catholic hierarchy has been in the forefront of opposition to abuses and inequality in countries such as Brazil and Chile, which are similarly ruled by conservative military institutions, church activism had been notably absent in Argentina.

The shift in the church's posture is attributed by informed officials in part to the relaxing of control by Argentina's military rulers and to growing civilian opposition to their rule and--more significantly--to the changing character of the country's Catholic hierarchy in the last five years.

More than one-third of Argentina's 85 bishops have retired or died in that period, and they have been replaced by younger men who, by and large, are more liberal and influenced by the Vatican's emphasis on social and humanitarian doctrine.

"The church is providing the moral guidance and direction for what everyone wants in Argentina," said Ubaldo Calabresi, the Vatican representative. "That is normalization and a return to democracy."

"There has been a change in the Catholic episcopate, and though they have not taken sides against the government, there is a distance now," said one Argentine priest and church scholar. "There is a disillusionment now with military governments and the religion of freedom is being very strongly emphasized."

Church leaders are quick to stress that their pronouncements do not imply direct confrontation with the military government.

Yet at the same time, the church's call for "national reconciliation" and a rebuilding of democratic institutions has been seized upon by opposition political and labor leaders as a powerful tool for forging compromises in the armed forces' slow "national reorganization process," which presently envisions a return to civilian government only under strict military controls.

There are also signs that tensions have increased between church and military leaders.

Most noticeably, the important post of Army vicar, last held by a highly conservative and influential archbishop, has been left vacant for more than a year by church leaders and military officials, who apparently are unable to agree on a nomination to forward to Rome.

The Catholic leadership also has been angered by the armed forces' refusal to accept the results of Pope John Paul II's personal mediation effort in a border dispute with Chile--creating a diplomatic impasse that church leaders consider insulting to the pope's moral authority and to his image as a world leader. After agreeing to papal intervention in the dispute, the government in effect dismissed the pope's recommendation after disagreeing with his conclusions.

The changes in the church and in the country's political situation have swung the balance away from conservative and nationalist elements in the Catholic episcopate that once led the church to support not only the 1976 military takeover, but also a series of earlier governments that were outspokenly Catholic as well as authoritarian.

The old church hierarchy supported Argentina's first modern military coup in 1930 by staunchly clericalist generals, and in the late 1960s large sectors of the Catholic establishment backed the rise of Gen. Juan Ongania, whose nationalist government placed Catholic leaders in powerful positions.

When the armed forces ousted the government of Isabel Peron in 1976, the church issued a pastoral letter saying the restriction of rights by the new rulers was justified by the political turbulence and terrorist violence then sweeping the country.

Now, however, both the church's nationalist, authoritarian inclinations and its consensus on a current "state of exception" for citizens rights have largely disappeared and church leaders, according to informed officials, would like to see a form of government more stable than the revolving door of generals and ineffectual civilians the country has endured for decades.

"What we are saying is that we are not in a war anymore," said Miguel Raspanti, an ebullient, 76-year-old bishop who heads the church's national charity organization, Caritas. "And so we are saying that there must be a normalizing of the country, and the normalization for Argentina is full democracy."

The church's position was dramatically signaled last July, when the bishops' conference issued a 75-page tract on "national reconciliation" that drew banner headlines in newspapers and quickly sold out in Buenos Aires bookstores. "Argentina is suffering a crisis of authority," the declaration said, and only "a healthy democracy will void the dangers" of "personal injustice, arbitrary banishments of groups or parties, and political conditions of various types that distort free expression by citizens."

Since then, leaders of the bishops' conference have dramatized their call for a "national unity in which no one is excluded" by holding a well-publicized meeting with the recently formed front of the country's major political parties, which are seeking negotiations with the military government.

Church leaders also permitted the country's most aggresssive opposition labor syndicate, the General Confederation of Labor, to organize a mass attended by about 10,000 persons at a Buenos Aires church in November to "pray for peace and work." Later the same month, the bishops issued a rare second pastoral message for the year that, under the title "National Reconstruction and Moral Order," called the country's high unemployment "a critical point."

While the church statements have avoided specific criticism or proposals of economic policies, the November message, like that of July, left the clear implication of dissatisfaction with the military government's conservative economic measures. "They always address the situation from the social point of view," said Ignacio Palacios Videla, a member of the church's lay commission on justice and peace. "But by emphasizing repeatedly the social effects, they are saying that the programs that created them are unjust."

More directly, the church hierarchy has clearly dropped its once relatively quiet approach to the thousands of disappearances and cases of lengthy imprisonment attributed to the military government.

The Catholic leadership first addressed charges of disappearances and torture in a 1977 pastoral letter, and repeated its "serious inquietude" in a later statement. But high church officials rarely spoke out in public on cases of disappearances--saying they preferred private negotiations with the military--and their joint statements were widely perceived as ambiguous and muted by expressions of understanding for the military's difficulties in combating leftist terrorists.

"The collective voice of the episcopate sounded . . . almost on the margin of events," noted political columnist J. Iglesias Rouco, "to the extent of making itself, for all practical purposes, almost inaudible."

"They wrote up their statements, and then they in a sense folded them up and put them in a drawer," said a priest who spent those years working in the Buenos Aires slums.

Church officials dispute those interpretations, but all agree that the new call for democracy was accompanied by the sharpest church statement yet on the military's excesses. The document contained a clear expression of concern for "the anguished situation of the families of the disappeared" and a flat judgment on the military rule that had not been made before: while guerrilla violence "darkened the country," the bishops said, "illegitimate repression also darkened the nation."

Now, in addition to such events as Papal Nuncio Calabresi's visit to political prisoners to celebrate Christmas mass, high leaders of the bishops' conference have been speaking out frequently on the country's estimated 6,000 to 15,000 "disappeared." "The only road that can take us to an authentic reconciliaton," announced Vicente Zaspe, the second vice president of the bishops' conference, last week, "is to arrive at the truth" over the missing.

"You're seeing a public position now that wasn't there before," said Carlos Floria, of the church-oriented journal Criterio. "For severals years, the attitude was to suspend the hard criticism--they thought they had to allow the country's social fabric to repair. Now, the church has moved back to a critical distance."