Pope John Paul II today strongly condemned the "anti-Christian methods" of revolutionary groups and called on Peruvian youth to seek peaceful reform through the "conversion of the heart."

In one of the most forceful statements of his eight-day-old tour through Latin America, the pope squarely attacked the appeal of radical ideologies in a country marked by both a strong political left and a growing Maoist guerrilla movement, the Sendero Luminoso or Shining Path.

"You rightly feel -- and should always feel -- the longing for a more just society," John Paul told thousands of youths who gathered at Lima's horse racing stadium late this afternoon. "But do not follow those who say that social injustice can only disappear through the hatred between classes or the resort to violence and other anti-Christian methods."

Instead, he said, only by following Christ could youth bring about "a new world, a better world.

"This does not mean cowardice, but the authentic spiritual value of those who know how to confront the world not with anger, not with violence, but with benevolence and amiability, defeating evil with good."

"If you want to be truly happy," John Paul declared to the cheering, flag-waving crowd, "seek identification with Christ."

The pope's statements continued an offensive against Marxist ideology and its use in social mobilization both inside and outside the church that has been scattered throughout his messages in Venezuela, Ecuador and Peru.

Here, however, his words have appeared to take on more force, matching the conditions of a country where more than 4,000 persons have been killed in political violence since 1980.

"Violence engenders violence," he said, quoting a recent Vatican document criticizing radical versions of Latin America's liberation theology movement. "It violates the human dignity of its victims and tarnishes the dignity of those who practice it."

While the Peruvian clergy have never advocated violence, a number argue that Marxism is useful in evaluating social realities. In addition, theologians such as the Rev. Gustavo Gutierrez, considered the first author to espouse liberation theology, argue that the church should help the poor organize to promote their economic interests.

While he has avoided direct criticism, the pope's remarks here have clearly run counter to some of the liberationists' thinking.

"The vision of the world and the life that the Gospel gives us and that is explained by Catholic social doctrine," he said, "promotes constructive action far more than any ideology, however attractive it may seem."

Speaking to the youth gathering, John Paul also reiterated his position that by choosing "a preferential option for the poor," the church should include "all the forms of poverty that exist in our world," such as "so many rich men who are terribly poor" in spirit.

The pope asked the youths for a "special solidarity" for "the victims of poverty that affects spiritual values," such as those who bear "above all the lack of religious freedom."

He also called on them to avoid "all of the traps that try to destroy the treasure of your youth -- those of drugs, of violence, of sin in general."

The pope, who last night issued a strong call to Peruvian clergy to obey church authorities, restated his criticism of "parallel" authorities tonight in an address to Peruvian bishops.

In an evident reference to Latin American theologians who have questioned the Vatican's strict hierarchy and control over the local church, he said any parallel authority would be "ecclesiastically unacceptable and pastorally sterile."

He also cited the example of St. Toribio de Mogrovejo, a Latin American who he said "knew how to guard for loyalty to the doctrine of the church" and "denounced the unjust systems applied against the indigenous people without having political aims or ideological motives."

The pontiff began a long day of activities with a visit to Arequipa, Peru's second largest city 600 miles southeast of Lima. After passing through the town by motorcade, he offered an outdoor mass attended by a crowd numbering in the tens of thousands.

As spectators held umbrellas or newspapers overhead to guard against a blazing morning sun, the pope beatified a Peruvian nun, Ana de los Angeles Monteagudo, who spent almost all of her 84 years cloistered in a local monastery during the 17th century. Beatification is the last step before canonization as a saint.