Many in the crowd said they were gratified by Benedict's recognition of their country's problems and said they felt reinvigorated in what they described as a daily struggle against criminality, corruption and economic hardship.
The pope delivered the message to an estimated 350,000 people against the backdrop of the Christ the King monument, one of the most important symbols of Mexican Christianity. The statue recalls a 1920s Roman Catholic uprising against the anti-clerical laws that forbade public worship services such as the one Benedict celebrated.
"We pray for him to help us, that there be no more violence in the country," said Lorena Diaz, 50, who owns a jeans factory in nearby Leon. "We pray that he gives us peace."
With his first visit to Mexico, the pontiff appeared to lay to rest doubts that he was a distant, cold pope who could never compare to the charisma and personal connection that his predecessor, John Paul II, forged over his five visits to Mexico. Many Mexicans said they were surprised by their depth of feeling for Benedict.
On Sunday, he charmed the crowd by donning a broad-brimmed Mexican sombrero.
"Some young people rejected the pope, saying he has an angry face. But now they see him like a grandfather," said Cristian Roberto Cerda Reynoso, 17, a seminarian from Leon. "I see the youth filled with excitement and enthusiasm."
He charmed them again later Sunday when he was serenaded by a mariachi band and presented with another sombrero at the entrance to the school where he was staying.
"I've made a lot of trips, but I've never been welcomed with such enthusiasm," Benedict told the wildly cheering crowd in off-the-cuff remarks. "Now I can understand why Pope John Paul II used to say, 'I feel like I'm a Mexican pope."'
Esther Villegas, a 36-year-old cosmetics vendor, said Benedict's image in Mexico has been changed greatly by the visit.
"We saw a lot of happiness in his face. We are used to seeing him with a harder appearance, but this time he looked happier, smiling," Villegas said. "A lot of people didn't care for him enough before, but now he has won us over."
Before Sunday's ceremony, the vast field was filled with noise, as people took pictures with cellphones and passed around food. But as the Mass started, all fell silent, some dropping to their knees in the dirt and gazing at the altar or giant video screens.
In his homily, Benedict encouraged Mexicans to purify their hearts to confront the sufferings, difficulties and evils of daily life. It has been a common theme in his first visit to Mexico as pope: On Saturday he urged the young to be messengers of peace in a country that has witnessed the deaths of more than 47,000 people in a drug war that has escalated during a government offensive against cartels.
"At this time when so many families are separated or forced to emigrate, when so many are suffering due to poverty, corruption, domestic violence, drug trafficking, the crisis of values and increased crime, we come to Mary in search of consolation, strength and hope," Benedict said in a prayer at the end of Mass.
The reference to Mary is particularly important for Mexicans, who revere the Virgin of Guadalupe as their patron saint, and he urged all of Latin America and the Caribbean to look to her for help. "She is the mother of the true God, who invites us to stay with faith and charity beneath her mantle, so as to overcome in this way all evil and to establish a more just and fraternal society."
Benedict's reference to immigration resonated in Guanajuato, which is one of the top three Mexican states sending migrant workers north.
"People leave for the good of their families," said Jose Porfirio Garcia Martinez, 56, an indigenous farmworker who came to the Mass with 35 others from Puebla, another area that has many migrants in the U.S. "For us it's difficult, not seeing them for 10 years, communicating by phone and by Internet."
The archbishop of Leon, Monsignor Jose Martin Rabago, told Benedict at the start of Mass that Mexicans needed a message of hope because they have been living in "fear, helplessness and grief" over the mass killings, kidnappings, extortion and other violence stemming from Mexico's drug trade.
"We know that this dramatic reality has perverse origins which are fed by poverty, lack of opportunities, the corruption, the impunity, the poor administration of justice and the cultural change which leads to the belief that this life is only worth living if it allows you to accumulate possessions and power quickly regardless of its consequences and costs," Rabago said.
Benedict wanted to come to Guanajuato because it was one of the parts of Mexico that John Paul II had never visited during his time in Mexico as pope. In addition, Benedict wanted to see and bless the Christ the King statue.
With its outstretched arms, the 72-foot (22-meter) bronze monument of Christ "expresses an identity of the Mexican people that contains a whole history in relation to the testimony of faith and those who fought for religious freedom at the time," said Monsignor Victor Rene Rodriguez, secretary general of the Mexican bishops conference.
Guanajuato state was the site of some of the key battles of the Cristero War, so-called because its protagonists said they were fighting for Christ the King. Historians say about 90,000 people died before peace was restored. The region remains Mexico's most conservatively Catholic.
While the pope drew a rapturous response from the faithful, his trip has not been without criticism, particularly concerning the church's treatment of children and sexual abuse.
Victims of Marcial Maciel, the founder of the influential, conservative Legionaries of Christ religious order, launched a book Saturday containing documents from the Vatican archives showing that Holy See officials knew for decades that Maciel was a drug addict who sexually abused his seminarians.
One of Maciel's most prominent victims, Juan Jose Vaca, followed up on Sunday with an open letter to the pope decrying the fact that he hadn't met with survivors of those abused by Maciel or other clerics, as he has during earlier foreign trips.
"Today, you are honoring the heroic memory of men who gave their lives in defense of their faith and religious liberty, the Cristeros," Vaca wrote, noting his own father had been a Cristero fighter. "Meanwhile for us, victims and survivors of other atrocities, not a word."
The 84-year-old pope, who will be going to Cuba on Monday, has made no explicit reference to abuse on this trip. But the Vatican spokesman, the Rev. Federico Lombardi, said the pope's words about the need to protect children from violence referred also to the need to protect them from priestly sexual violence.
Some other victims of Maciel have said they didn't want a meeting anyway because the pope had been head of the Vatican office that received their complaint against Maciel in 1998. It took the Vatican eight years before sentencing Maciel to a lifetime of penance and prayer for his crimes.
The pope did meet briefly on Saturday night with eight relatives of victims of violent crime. Lombardi said it wasn't a sit-down meeting so much as a brief greeting.
ABC13 reporters Erik Barajas and Christine Dobbyn are reporting on the Pope's visit from Mexico and Cuba. Stay with ABC13 Eyewitness News and abc13.com for the latest coverage on the Pope's travels.