SAN CRISTÓBAL DE LAS CASAS, Mexico—Pope Francis blasted the “oppression, mistreatment and humiliation” of indigenous peoples in a multilingual Mass on Monday in this mostly Mayan highland town in southern Mexico, and said the rest of the world has much to learn from indigenous culture.

The Mass was in Spanish, the language of the conquistadors, but also in three Maya languages—Tzotzil, Tzeltal and Ch’ol.

“Your...