SAN CRISTOBAL DE LAS CASAS, Mexico (AP) -- Pope Francis is celebrating Mexico's Indians on Monday with a visit to heavily indigenous Chiapas state, where he will preside over a Mass in three native languages thanks to a new Vatican decree approving their use in liturgy.

But the visit, at the midway mark of Francis' five-day trip to Mexico, is also aimed at boosting the faith in the least Catholic state in Mexico.

History's first Latin American pope has already issued a sweeping apology for the Catholic Church's colonial-era crimes against the continent's indigenous. On Monday, he'll go further by celebrating their culture in ways the local church hierarchy has often sought to play down, in a clear demonstration of his belief that Indians have an important role to play in Mexico today.

"I ask you to show singular tenderness in the way you regard indigenous peoples and their fascinating but not infrequently decimated cultures," Francis told Mexico's bishops Saturday in a speech outlining their marching orders. "The indigenous people of Mexico still await true recognition of the richness of their contribution and the fruitfulness of their presence."

The Mexican hierarchy has long bristled at the region's "Indian church," a mixture of Catholicism and indigenous culture that includes pine boughs, eggs and references to "God the Father and Mother" in services. It was a tradition that was embraced by the late bishop of San Cristobal de las Casas, Samuel Ruiz, who ran afoul of both the Mexican church and the Vatican at times for his use of the local ways.

Monday's Mass will include readings, prayers and hymns in the three main indigenous languages of Chiapas: Tzeltal, Tzotzil and Chol, which are spoken by just over 1 million people, according to Mexico's latest census. The Vatican has said the pope would present the official decree authorizing the languages to be used, some 50 years after the Second Vatican Council paved the way for Mass to be celebrated in the vernacular rather than in Latin.

"Vatican II in liturgy finally comes to Chiapas," said the Rev. Manuel Dorantes, an assistant Vatican spokesman who is from Mexico.

Despite the pope's overture, residents of Chiapas said they believe Francis is coming mostly to confirm their faith, not their status as indigenous.

"It doesn't matter that I'm indigenous; I think it's more that I'm Catholic," said Emanuel Gomez, a 22-year-old Tzotzil who planned to attend the Mass. "The pope comes to encourage our hearts and faith as Catholics."

He added, though, that the visit would "lift us up so we don't feel scorned by the powerful and rich."

According to government statistics about 46 percent of Mexicans were living in poverty in 2014. That number surges in Chiapas, where some 76 percent were living in poverty, 32 percent in extreme poverty.

Francis has insisted that his is a "poor church, for the poor," and was expected to address the problems of poverty and marginalization Monday. After the Mass, Francis was scheduled to hear testimony from a handful of Chiapas families about the hardships they face.