Mexico remains majority Catholic, around 78 to 80 percent per most recent census figures and estimates including Pew Research's Religious Composition of the World, 2010-2020, though the Catholic share has declined from over 90 percent decades ago as Protestant, especially Pentecostal and evangelical, communities and religiously unaffiliated Mexicans have grown substantially.
Spanish colonization following the 1519 to 1521 conquest of the Aztec Empire brought mass forced Christianization of Mexico's indigenous population, though the 1531 reported apparitions of the Virgin of Guadalupe to the indigenous convert Juan Diego, producing an image now housed in Mexico City's Basilica of Guadalupe, one of Catholicism's most visited pilgrimage sites worldwide, became a powerful vehicle for indigenous Catholic identity and is widely credited by historians with accelerating and localizing indigenous conversion by presenting Mary in indigenous-coded imagery.
Pre-Hispanic Mesoamerican religion, including Aztec, Maya and Zapotec traditions centered on complex calendars, human sacrifice and a vast pantheon led by deities such as Huitzilopochtli and Quetzalcoatl, was suppressed but never entirely eliminated, and syncretic practices blending Catholic saints with indigenous ritual, including the Day of the Dead's ancestor-honoring customs, remain widespread and are recognized by UNESCO as intangible cultural heritage.