Pope Benedict, speaking from Cuba's biggest stage, urged Cubans on Wednesday to search for authentic freedom as their country changes and pressed the island's communist government to give the Catholic Church more liberties, including the right to teach religion in schools and run universities.
The 84-year-old pope celebrated an open-air Mass for some 300,000 people in Havana's Revolution Square, the centrepiece of a trip that began with a blast at communism and will end with a visit with Fidel Castro.
Crowds began gathering during the night to hear the leader of the world's 1.2 billon Catholics speak in the sprawling plaza that Castro, 85, used to fill with big crowds and fiery revolutionary rhetoric in hours-long speeches.
Surrounded by ten-story high images of Castro's revolutionary comrades Ernesto Che Guevara and Camilo Cienfuegos, the pope read a sermon that continued one of the main themes of his trip - that Cuba should build a more open society, based on truth, justice and reconciliation.
The truth is a desire of the human person, the search for which always supposes the exercise of authentic freedom, he said.
In an apparent dig at Marxism, the pope also said some wrongly interpret this search for the truth, leading them to irrationality and fanaticism; they close themselves in 'their truth,' and try to impose it on others.
Hours before the Mass began, the area was filled with people waving Cuban flags and wearing broad hats and holding umbrellas to shield them from the sun. They wildly welcomed the successor of the much-beloved Pope John Paul, who made a historic, groundbreaking trip to Cuba in 1998 and preached from the same square.
Benedict, wearing purple vestments, read out a virtual shopping list of rights the Church still lacked in Cuba as President Raul Castro, Fidel's younger brother, sat in the front row. Both of the Castro brothers were educated by Jesuits, the worldwide Catholic order.
To carry out this duty, she must count on basic religious freedom, which consists in her being able to proclaim and to celebrate her faith also in public, bringing to others the message of love, reconciliation and peace which Jesus brought to the world, he said.
While Benedict acknowledged with joy the great improvements since John Paul's visit, he added: Nonetheless, this must continue forwards, and I wish to encourage the country's government authorities to strengthen what has already been achieved and advance along this path of genuine service to the true good of Cuban society as a whole.
The faithful could be at once a citizen and a believer, the pope assured the government, adding that strengthening religious freedom consolidates social bonds and lays the groundwork for securing the rights of future generations.
This is why the Church seeks to give witness by her preaching and teaching, both in catechesis and in schools and universities, he said.
Since his arrival in the eastern city of Santiago, the pontiff has spoken of Cuba's need for reconciliation and a more open society, with the Church at its side as a buffer against trauma or social upheaval.
We hope he brings peace, and to wars, and an end to the US embargo, said Belkis Martin Rodriguez, 49, walking to Revolution Square dressed in jean shorts, with her mother and 8-year-old son.
Asked if she hoped the visit would bring reconciliation between the communist government, dissidents and exiles in Miami, she said: Let each remain in their own place. If people left for Miami, let them stay there and be happy. Let the Church stick to its own field, religion, and let the government handle the politics.
In talks on Tuesday with Raul Castro, the pope urged a bigger role for the Church and asked that the government consider making Good Friday, the day Christians commemorate Christ's death, a national holiday. Good Friday is less than two weeks away.
Fidel Castro reinstated Christmas as a holiday ahead of the landmark visit of John Paul that helped improve long-strained Church-state relations.
The Vatican during Tuesday's meetings also made several humanitarian requests, without giving details but possibly having to do with political prisoners or jailed American contractor Alan Gross, who is serving a 15-year sentence for illegally installing Internet networks on the communist-run island.
FIDEL MEETING POPE
Fidel Castro said on Tuesday in one of his columns, or Reflections, published on the Internet that he would meet briefly with the German pope before he returns to Rome.
With pleasure, I will greet His Excellency Pope Benedict XVI as I did with John Paul II, wrote Castro, who is now mostly retired but still occasionally writes columns and meets with visiting leaders.
He said he decided to request a few minutes of his very occupied time when I learned from the mouth of our Foreign Minister Bruno Rodriguez that modest and simple contact would please (the Pope), Castro said.
The meeting of two octogenarian world figures with widely divergent political views would be another high point in what has been a more eventful papal trip than many had expected.
At a time when Church-state relations are the warmest they've been since the 1959 revolution, Benedict has not been afraid to poke the Cuban government in some sensitive places.
On the flight to Mexico beginning his trip on Friday, the pope said communism does not correspond with reality and that Cuba needs a new economic model.
Upon his arrival, he made thinly-veiled references to Cuban dissidents, political prisoners, Cuban exiles and asked the island's patron saint, the Virgin of Charity of El Cobre, to guide the future of this beloved nation in the ways of justice, peace, freedom and reconciliation.
His Monday evening mass in Santiago began with a man in the crowd shouting down with communism and being hustled off by security agents.
President Castro has launched economic changes aimed at strengthening communism for the future, but Marino Murillo, a vice president in the Council of Ministers and the country's economic reforms czar, made it clear that change to Cuba's one-party political system is not in the works.
In Cuba there won't be political reform, he said at a news conference at Havana's Hotel Nacional, the international press centre for the pope visit. We are talking about the update of the Cuban economic model to make our socialism sustainable.
Murillo said the government welcomed all ideas, but would not allow them to be imposed on the country.
In response, Vatican spokesman Father Federico Lombardi said the Church is not trying to impose solutions. We know it is a long road and that the history of Cuba is complex.
(Editing by David Adams and Philip Barbara)