Pope Benedict XVI demanded more freedom for the Catholic Church in communist-run Cuba and preached against "fanaticism" in an unusually political sermon before returning on a flight to Rome Wednesday evening.

Benedict delivered his address earlier in the day before hundreds of thousands at Revolution Plaza, with President Raul Castro in the front row. Later, the president's brother, revolutionary leader Fidel, grilled the pontiff on changes in church liturgy and his role as spiritual leader of the world's Catholics, a Vatican spokesman said.

Benedict's homily was a not-so-subtle jab at the island's leadership before a vast crowd of Cubans, both in the sprawling plaza and watching on television. But he also clearly urged an end to Cuba's isolation, a reference to the 50-year U.S. economic embargo and the inability of 11 American presidents and brothers Fidel and Raul Castro to forge peace.

"Cuba and the world need change, but this will occur only if each one is in a position to seek the truth and chooses the way of love, sowing reconciliation and fraternity," Benedict said. The remark built upon the famed call of his predecessor, John Paul II, who said in his groundbreaking 1998 visit that Cuba should "open itself up to the world, and may the world open itself up to Cuba."

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Pope Benedict XVI and Cuban President Raul Castro look at a statue of the Virgin of Charity of El Cobre, patron saint of Cuba, which the Pope received as a gift from Castro, at the Revolution Palace in Havana on Tuesday. (Adalberto Roque/Reuters)

With the country's leadership listening from front-row seats, Benedict referred to the biblical account of how youths persecuted by the Babylonian king "preferred to face death by fire rather than betray their conscience and their faith."

He said people find freedom when they seek the truth that Christianity offers.

"On the other hand there are those who wrongly interpret this search for the truth, leading them to irrationality and fanaticism; they close themselves up in 'their truth' and try to impose it on others," he said from the altar, backed by an image of Cuba's revolutionary hero Ernesto "Che" Guevara.

Still, it was unclear how much the pope's message resonated with ordinary Cubans.

Many in the crowd had trouble hearing him over the loudspeakers, and others said it was hard to understand the dense biblical message delivered by the pope in a soft voice.

"I don't understand this Mass at all. I don't have an education in these things and I know nothing about religion," said Mario Mendez, a 19-year-old communications student. "On top of that, I can't hear anything."

U.S. contractor case

The Obama administration says it would be grateful if Pope Benedict XVI raised with Cuban officials the case of American contractor Alan Gross, jailed on suspicion of espionage.  

The State Department said Wednesday it made the request to the Vatican and the papal nuncio in Washington before the Pope arrived in Cuba this week.

— The Associated Press 

Benedict's comments were an unmistakable criticism of the Cuban reality even if the pope didn't mention the government by name, said the Rev. Joseph Fessio, a former student of Benedict's. As his U.S. publisher, Fessio knows well the pope's message and how he transmits it, particularly the watchwords of his pontificate: truth and freedom.

"Does anyone in Cuba not know how the words themselves condemn the reality there?" Fessio said in an email.

Benedict's trip was aimed largely at building a greater place for his church in the least Catholic nation in Latin America. In his homily, he urged authorities to let the church more freely preach its message and educate its young in the faith in schools and universities. Religious schools were closed after the Castros came to power a half-century ago.

Castro asked what it's like to be pope

He praised openings for religion made since the early 1990s, when the government abandoned official atheism and slowly warmed to the church, a pattern that accelerated with the visit of Pope John Paul II.

"It must be said with joy that in Cuba steps have been taken to enable the church to carry out her essential mission of expressing her faith openly and publicly," Benedict said. "Nonetheless this must continue forward" for the good of Cuban society.

During the 30-minute meeting between the pope and Fidel Castro at the Vatican's Embassy, the retired Cuban leader — a one-time altar boy who was educated by Jesuit priests — essentially interviewed Benedict, asking him about the changes in church teachings since he was a child, what it's like to be a pope and the challenges facing humanity today, said the Vatican spokesman, the Rev. Federico Lombardi.

Benedict, meanwhile, raised issues such as the role of freedom and liberty, Lombardi said.

Photos showed Fidel, wearing a dark warm-up jacket, gesturing with one hand while clutching a man's arm with the other. The pope, wearing his white cassock, leaned in slightly and smiled.

Castro introduced his companion, Dalia Soto del Valle, and his two children and asked the pope to send him some books to elaborate on the topics they had discussed, Lombardi said.

'Viva Cuba! Viva el Papa!'

The meeting began with some jokes about their ages. Castro is 85, Benedict reaches that milestone next month. "Yes, I'm old, but I can still do my job," Lombardi quoted the pope as saying.

He described the meeting as serene, intense, animated and cordial.

At the morning Mass, banners large and small filled the plaza, and many took shade under umbrellas as announcers shouted "Viva Cuba! Viva el Papa!"

"The pope is something big for Cubans," said Carlos Herrera, a tourism worker who came to the plaza with his wife. "I come to hear his words, wise words for the Cuban people. That helps us. It gives us peace, it gives us unity. We do not want war."

The Vatican said the plaza holds 600,000 people and it appeared nearly full, though many Cubans drifted off after registering their presence with teachers and employers.

During the event, an Associated Press journalist saw a man in the crowd led briskly away by people in civilian clothing after he shouted "Pope, don't leave until communism falls!" It was not clear who he was or where he was taken. The incident was similar to another during the pope's Mass in Santiago Monday, when a man shouted anti-government slogans before being hustled away.