To Sin No more is a valuable reference for scholars interested in the Franciscan missions in the Americas in the late seventeenth to early nineteenth centuries. David Rex Galindo reconstructs the administrative structures, institutional disputes, daily lives, and missionary project of the Franciscans of the apostolic colleges (colegios apostólicos de Propaganda Fide). His research is based upon intensive and original research of Franciscan archives in Bolivia, Mexico, Spain, and the Catholic Mission Archives in Texas. Rex Galindo systematizes his findings and presents a clear picture of the Franciscan missions using tables that list the colleges, illustrate their demographics, their recruitment process, and their quotidian routines, as well as maps (created by Iván López Nieto) of the Franciscan colegios de propaganda fide in Spain, New Spain, and South America. By focusing on the apostolic colleges, To Sin No more provides new insights into the institutional infrastructure of the Franciscans’ missionary project as “each college, acting as a hub of missionary expansion, extended its missionary program over urban areas and hinterlands along with the rural countryside” (182).

To Sin No more focuses on the well-documented period of the Propaganda Fide (established in 1622). The Propaganda Fide period marks a change from the earlier period in the way Franciscan missions were organized and the Propaganda Fide colleges became key institutions in the Franciscans’ missionary network. Rex Galindo provides important contextualization of this period, including the climate of reform political changes within New Spain (including the Pueblo Revolt of 1680) and factional tensions within the Order (especially between Spanish and American born friars). The Franciscan missions, which had resisted attempts of secularization through the seventeenth century faced new pressures in the eighteenth. Religious orders were blamed for Spanish decadence and the Arbitristas were particular enemies of religious expansion (27). Rex Galindo observes that the expansion of the Franciscans’ Propaganda Fide institutions is significant as it coincided with opposition to the expansion of other religious orders as (4). The first part of the book focuses on the institutional history of the colleges. Chapter 1 examines how Franciscans bypassed royal cédulas banning the foundations of new mendicant institutions in the eighteenth century by establishing the Propaganda Fide colleges within existing Franciscan institutions. Chapter 2 examines the demographics of the Franciscans’ Propaganda Fide colleges, showing that most missionaries came from Peninsula Spain.

Rex Galindo argues that the Propaganda Fide colleges are central to understanding the new period of Franciscan mission that developed at the end of the seventeenth century. Propaganda fide marked a new phase in the Catholic's mission, aimed at addressing recidivism in a systematic way. The book's title, To Sin No More, quotes the prayer recited during penance to overcome the failure of sin (18). The book's central argument is laid out in the second part of the book, which focuses on the Catholic concept and practice of soteriology in this period. Rex Galindo argues that in the Propaganda Fide period the Catholic understanding of conversion was as a longitudinal process, to be continually addressed by old and new Catholics through penance. Rex Galindo claims to examine conversion “from the same angle that a Franciscan friar (and for that matter, a Catholic cleric) would have understood it,” explaining that “it implied turning non-Christians into Catholics as much as revitalizing the faith of Catholics” (15).

Rex Galindo's key maneuver is to suggest a rethinking of the historiography of conversion conceives of conversion as an ongoing transformation experienced by Amerindians and missionaries. Rex Galindo contends that “we need to study missionaries with the same sensibilities as we now devote to Indians” (14). For Rex Galindo, the “internal metamorphosis” of conversion was common to missionaries and natives (15). Using Franciscan missionary sources Rex Galindo claims to represent a “helicoidal model” that “fits the Catholic understanding of conversion” (18). However, this strips the process of conversion from the context of colonialism in which it was embedded. Franciscans might well have understood conversion to be an ongoing process shared by missionaries and natives but this does not reflect the power asymmetries of colonialism. Rex Galindo discusses the violence performed during acts of penance but not the broader context of violence in the colonial society.

Rex Galindo begins the book with a reference to Pope Francis's canonization of the Franciscan missionary Junípero de la Serra, and compliment of his missionary zeal, writing that “to Francis and to many others, Serra embodied the true Christian who selflessly left him homeland, his relatives, and his life of comfort for the missionary hardships in America” (1). Rex Galindo does not counter this with the evidence of Junípero de la Serra's crimes against the indigenous people of the Americas and the controversies that surrounded him. Instead he writes that “Franciscan missionaries taught Catholicism to convert and save humankind” (2). This introduction indicates the tendency to take Franciscan sources at face value, common in Franciscan historiography, rather than examining their ambiguities and contribution to colonial projects.