The physical signs of Roman Catholicism pervade the Mexican countryside. Colonial churches and neighborhood chapels, wayside shrines, and mountaintop crosses dot the landscape. Catholicism also permeates the traditional cultures of rural communities, although this ideational influence is less immediately obvious. It is often couched in enigmatic idiom and imagery, and it is further obscured by the vestiges of pagan customs and the anticlerical attitudes of many villagers. These heterodox tendencies have even led some observers to conclude that Catholicism in rural Mexico is little more than a thin veneer on indigenous practice.

In Mary, Michael, and Lucifer John M. Ingham attempts to develop a modern semiotic and structuralist interpretation of traditional Mexican culture, an interpretation that accounts for the culture's apparent heterodoxy. Drawing on field research in Tlayacapan, Morelos, a village in the central highlands, he shows that nearly every domain of folk culture is informed with religious meaning. More precisely, the Catholic categories of spirit, nature, and evil compose the basic framework of the villagers' social relations and subjective experiences.