Religion is an important motif within The Guardians. Although Gabo and Father Juan Bosco are the novel’s only devoutly religious characters, both Regina and Miguel have a complex relationship with religion and religiosity. This motif allows Castillo to explore the Borderlands’ complex identity politics and develop the theme of Identity in the Borderlands.

The Texas/New Mexico/Mexico region where The Guardians is set has a long and fraught religious history. Settled first by Indigenous peoples, it was colonized by Spain and then invaded by the US. Catholicism, the religion to which Gabo is devoted but about which Regina and Miguel have serious reservations, was part of Spain’s assimilationist project in the region, and its role within Indigenous communities in the Borderlands is fiercely contested. Many Indigenous communities still feel that their own spiritual and religious practices were subjected to erasure during the era in which they were made to convert to the religion of their colonizers and oppressors. However, for those who identify as Mexican, Hispanic, Chicano, or Anglo, Catholicism is often a key part of their identitarian framework. This identification has deepened over the centuries that Catholicism has been practiced in this region, blending with Indigenous traditions to create a unique form of Catholicism.