THE SOURCE: "Religious Competition and Ethnic Mobilization in Latin America: Why the Catholic Church Promotes Indigenous Movements in Mexico" by Guillermo Trejo, in American Political Science Review, Aug. 2009.
THE LATTER DECADES OF THE 20th century were an explosive time for the Mexican Catholic Church. Clergy across the country joined radical indigenous peasant movements to protest the Mexican government's human rights abuses and demand land redistribution. Many onlookers regarded the church's newfound political awareness as a consequence of liberation theology, a doctrine sweeping across Latin America that sees political activism in the pursuit of economic and social justice as part of the struggle for salvation.
But Guillermo Trejo, a political scientist at Duke University, says that explanation falls short, overstating the extent to which clergy supported political movements and ignoring regional variations in their involvement. A better explanation: the growing presence of Protestants.
Trejo's theory looks at religions as economists look at goods. When a new sect threatens a church's dominance (external shock), the established church (a "lazy monopoly," in the words of Adam Smith) will vie for its members' adherence by one-upping the upstart. In the case of the Catholic Church in Mexico, that meant becoming a major institutional force in the rural indigenous movements for land redistribution when Presbyterians and other mainline Protestant sects began to appear.
Not all instances …