Remember that the Spanish conquista of the Aztecs, with all its brutality, death, and disease, took place with the blessing of the Catholic Church. Most of the surviving indigenous folk converted to Catholicism, but some memory of what happened to them undoubtedly survived. But the main reason for rebellion against the Church was probably the Bolshevik Revolution. Mexico has, for the last 100 years, flirted with communism. The Mexican Communist Party did not last long; it was absorbed into another party, which was in turn absorbed by another, in their "multiparty" system. I put the word in quotes because in reality the country is run by two competing factions: a corrupt oligarchy and a bunch of narco cartels that fight each other as much as they fight the government (elements of which are bought off by the cartels). But there is still a strong socialist strain in Mexican politics, mostly centered in the present-day party known as the PRD.