The excitement surrounding the journey of Pope John Paul II to the Latin American Bishops' Conference in Puebla, Mexico, has momentarily obscured the bitter two-year struggle for control of that pivotal gathering.

But when the colorful opening ceremonies are over and the 350 or so church leaders begin serious deliberations on Monday, it appears likely that conservative forces in the church -- with the blessing of the Vatican -- will be in control.

The conservative presence will be felt in the direction of the conference, in the preparatory documents that will form the basis of discussion, and in the selection of bishops and others participating both as voting delegates and as advisers and official observers.

A little more than 10 years ago, Latin American Catholics met in a similar conclave in Medellin, Colombia. The conclusions of that meeting paved the way for a new "theology of liberation" that allied the church with the poor and the oppressed, putting it in conflict with the oppressors, which in Latin America often meant totalitarian governments.

In countries such as Brazil, El Salvador and Chile, priests have died along with their people defending human rights and even bishops are not immune to arrest and police harassment. In Rio de Janeiro, Bishop Adriano Hypolito, who fought to improve the lot of slum-dwellers, was kidnapped, beaten, stripped and painted red by anticommunist vigilantes.

In El Salvador earlier this month, Archbishop Oscar A. Romero, in a mass for a young priest killed in a government raid on a retreat house, said that in the conflict between the government and the people "the church is with the people." It was the fourth time in two years that Romero had buried one of his priests killed by progovernment forces.

For other Latin American churchmen, however, liberation theology and a tendency toward Marxist analysis os social and economic problems, is seen as a threat to the church.

One who holds this view is Alfonso Lopez Trujillo, who was chosen by the other bishops secretary general of CELAM, the acronym in Spanish of the Latin American bishops' conference.

The eight-man team which Lopez Trujillo, who was himself made a bishop last year, named in 1977 to write the preparatory document for the Puebla conference produced a 214-page report that, predictably was unsatisfactory to liberation theologians.

Sent to the hierarchies of everey Latin American country, it was sharply criticized. The Brazilizn bishops' conference, for instance, appended more than 1,000 amendments, changes and complaints when they considered it last spring.

"It is a dismal document, full of fears," according to the Rev. Sergio Torres, a Chilean priest who heads a group called Theology in the Americas. "The reality is that it betrays Medellin."

The Rev. James R. Brockman, associate editor of the Jesuit weekly journal America, writes in the Jan. 27 issue that the document blamed the erosion of the faith of Catholics on "the secularization of society and chaotic process of urbanization which tears millions away from their roots in rural society and accepted beliefs."

Brockman added that the document notes "the present military regimes, while marked by lamentable abuses of power," have arisen as a reaction to "the economic and social chaos that menaced civil lite... In the face of tension and disorder, recourse to force is considered inevitable. Critics objected that such a detached treatment seemed to be an apology for the repression of human striving for justice and the decency of life."

The preparatory document, and the criticisms it attracted, was reconsidered, this time by a somewhat more representative group of churchmen. A revised report, called the Working Document, was distributed last August.

Critics of the first document acknowledged some improvements, but it still "doen't pick up the spirit of Medellin," observed one scholar of the Latin American church, who asked not to be identified.

The list of participants in Puebla, all of whom have been approved by the Vatican, appears to be weighted on the conservative side.

The selection process itself, Brookman points out, was geared to provide underrepresentation of Brazilians who, he says, "are the most outspoken and least conservative on the hemisphere." While Brazil accounts for narly a third of all Latin American Catholics, it will have "only about one-fourth of the elected delegates and only three of the 35 ex-officio delegates," he said.

In addition to the delegates chosen by their respective episcopal cnferences, the Vatican named 12 additional prelates, characterized by Catholic author Gary MacEoin as "all either conervative or extremely conservative."

Included in the Vatican's dozen are two who hold the rank of general in the armed forces of their respective countries: Cardinal Anibal Munoz Duque of Bogota, Colombia and Archbishop Alcides Mendoza Castor of Pederodiana, Peru.

There is a persistent, but unconfirmed, bit of Vatican lore which holds that this list of rightist prelates, presumably drawn up by Cardinal Sebastino Baggio in his role as head of the Pontifical Commission for Latin America, was among the papers found clutched in the hand of Pope John Paul I at his death.

Another significant clue as to the intent of the Puebla planners is the absence from the list of conference periti , or theological adcvisers, of any of Latin America's liberation theologians, several of whom have won world-wide reputations in the decade since Medellin. The best known, Gustavo Gutierrez, is known to have been nominated by the Chilean bishops, but somewhere, his name was cut from the approved list.

"None of the well-known Latin American theologians are on the list," said Thomas Quigley, Latin America expert for the U.S. Catholic bishops.