Playing out in parallel to the papal visit is political unrest in Brazil, where widespread anti-government protests that began last month have continued and are expected to take place right outside Rio's Guanabara Palace, the seat of state power where Francis is to meet with President Dilma Rousseff on Monday evening shortly after his arrival.
With the exception of gay rights groups and others angered by the church's doctrine against abortion and same-sex marriages, the target of most protesters won't be Francis but the government and political corruption. The pontiff is said to support Brazilians peacefully taking to the streets, and when he served as a cardinal in Buenos Aires he didn't shy from conflict with Argentina's leaders as he railed against corruption.
The pope will likely avoid hot-button issues like abortion and same-sex marriages while in Brazil, and focus on his message that the church should put its attention on the poor and that clergy must lead a humble life.
Brazil allows abortions only in cases of rape or risk to a mother's life or if a fetus is brainless, and the nation's supreme court in 2011 approved civil unions for same-sex couples. State courts have since allowed those unions to become full-fledged marriages.
The Catholic Church is not as active in politics in Brazil as it is in other Latin American nations, though it strongly opposes any efforts to loosen abortion laws and took part in the legal argument against civil unions when the matter was before the top court.
When Francis talks with Rousseff, they are likely to focus on the poor. Upon taking office, the Brazilian leader declared that eradicating extreme poverty was her top goal as president, and she has expanded a network of social welfare programs that have helped lift almost 30 million Brazilians out of poverty in the last decade.
"The good thing from a social perspective is that he understands the increasing stratification of wealth in Latin America," said Joseph Palacios, a sociologist at Georgetown University and former Catholic priest who has studied the church.
"Unlike his predecessors, who had a theoretical understanding, Francis has a pastoral understanding honed by living and working in working-class neighborhoods of Buenos Aires. All of his understanding of poverty and other social issues appear to be based on his experiences, not theory or doctrine."
That's evident to Maria Nascimento, a 60-year-old Catholic living in the Varginha slum where Francis will pay a visit this week.
"God chose wisely when he decided to send this humble man to lead the church. He's loved in this community because he's talking about poor people," she said, standing in her kitchen where photos of grandchildren's baptisms were stuck to her refrigerator with magnets.
"There's going to be a huge impact on Brazil after he has come and left, after his feet have walked these streets in our slum. He's going to help the church in Brazil, the love here for him is growing so fast."