VATICAN CITY — Pope Francis is calling for Latin America to care for its poorest and most marginalized, those who have been “enslaved” and exploited by an economic system that he said treats them as useless.

Francis deviated from his homily on an important Latin American feast day Friday to hammer home a point he made for years as archbishop of Buenos Aires and now as pope.

The Argentine Jesuit said he prayed that the continent would be shaped in the future by attention to the poor and persecuted, “by those for whom today the idolatry of a culture of waste relegates them to a category of slaves, objects of exploitation or simply wasted.”

He hoped the continent’s future would balance justice with reconciliation, scientific development with human wisdom and suffering with hope.

The feast of Our Lady of Guadalupe is one of the region’s important holidays. Millions make the pilgrimage to a Mexican basilica to honor the virgin said to have appeared to an Indian peasant on Dec. 12, 1531.

To mark the feast, Francis’ Mass featured Argentine folk hymns of the “Misa Criolla,” one of the first Masses composed in the vernacular after the liberating reforms of Vatican II. Francis has said the Spanish-language hymns, haunting and accompanied by folk percussion, were an important step in the church’s development in Latin America.

The late Argentine composer Ariel Ramírez presented “Misa Criolla” to Pope Paul VI on the same feast day 50 years ago.

Ramirez’s son conducted an Argentine chorus for Friday’s Mass, made even more colorful by a gaggle of children holding flags of the continent behind the altar of St. Peter’s.