Christianity was brought to Latin America by the Spanish and Portuguese conquerors of North, Central, and South America in the 16th cent. Sponsored by Ferdinand V and Isabella (the ‘Catholic Kings’), they came to the Americas just after the reconquest of Spain and Portugal from the Muslim Moors of North Africa (completed in 1492, a few months before Columbus's ‘discovery’ of America) and so brought with them a sense of religious citizenship which conflated the RC faith with fealty to the Crown. In the 1494 Treaty of Tordesillas between Spain and Portugal, Pope Alexander VI confirmed their claims to the New World on the basis of their ability to baptize its inhabitants and instruct them in the faith. The Vatican granted to Spain and Portugal the patronato real de las Indias, which gave their sovereigns the right to appoint all bishops within their territories, sealing the bond between the Church and Crown.
Franciscan, Dominican, and Augustinian friars, and later the Jesuits, preached among the indigenous groups of the Americas, with varying degrees of success. The early missionary orders who worked to convert America's great native peoples—the Aztecs of Mexico, the Incas of Peru, the Maya of Guatemala and Yucatán—met with initial resistance, but eventually proved successful, both through coercion and what Bartolomé de Las Casas called ‘peaceful persuasion’, in converting the indigenous people from their pre-hispanic polytheistic religions to Christianity. The Jesuits in the second half of the 16th cent. became the empire builders of New World Catholicism, founding churches, schools, universities, and missions along the distant frontiers of Mexico and Brazil. In the 17th cent. their missions among the Guaraní Indians of Paraguay (based partly on Thomas More's Utopia) were among the best known RC missions. The Jesuits were expelled from Latin America in 1767.
By the time that most Latin American countries gained their independence in the early 19th cent. the RC Church was the single most pervasive and influential colonial institution. It was the largest landholder in Ibero–America and managed wealth through various Church-owned financial assets; it ran every institution of higher learning; it controlled the political and intellectual life of the colonies through the Inquisition; and it had an active or passive presence through parish life in virtually every community. Viewing the RC Church as a conservative and atavistic competitor for power, the new liberal national governments sought to replace their citizens' loyalty to the Church with nationalism. Influenced by the Deism of the French and American revolutions, new national governments enacted anti-clerical policies that much reduced the Church's institutional presence in many Latin American countries in the course of the 19th and early 20th cents. Nevertheless Catholicism remained the dominant presence on the spiritual landscape of Latin America, an enduring reflection of what historians have called the ‘spiritual conquest of Latin America’. The conquest was in reality incomplete, as evidenced by the enduring presence of indigenous religion mixed with Catholic beliefs and rituals, a practice known variously as ‘folk Catholicism’, ‘religious syncretism’ or ‘creolized religion’ that is still common in regions that have large indigenous populations, such as southern Mexico, Guatemala, Ecuador, and Peru. Within areas with a sizable population of African descent, such as Brazil and the Caribbean, African religious beliefs and practices have merged with Catholicism to form diasporan religions that give the names of Catholic saints to African gods, and whose adherents engage in spirit possession and blood sacrifices which have no parallel in orthodox Catholicism.