Abstract: This article explores the relationship between religiosity—as experiential and practical religious involvement—and family styles—as effective kinship expectations and configurations. We begin by identifying three gaps and one risk in the previous literature: excessive focus on (Evangelical) conversion; the paucity of comparative Catholic/Evangelical studies; the absence of an extended family and intergenerational approach; and, although to a lesser extent, a risk of conflation of the religious phenomenon. Based on ethnographic observations and interviews conducted in a low-income neighborhood in Santiago, we investigated native Catholic and Evangelical individuals and couples with similar levels of religiosity and socioeconomic status. We have observed two contrasting family styles. While among Catholics, we found a deep appreciation of intergenerational solidarity with a matrifocal bias, with a secondary importance on the marital relationship; among Evangelicals, we observed a strong conjugality and relative relegation of intergenerational relationships. We explore these results using the lens of “affinities” between religious and family spheres, close to Max Weber’s classic concept of elective affinities. Evangelical religiosity produces solid boundaries with the secular world, including the influence of contextual family culture and non-nuclear kin, combined with an emphasis on individual autonomy and responsibility, which correlates with the notion of conjugality as an elective bond. Catholic religiosity is instead much more tolerant of the secular world, allowing a contextual family culture to permeate family configurations. The Catholic emphasis on Grace as an unconditional and gratuitous divine act, combined with popular devotion to Mary, reinforces the centrality of matrifocal intergenerational ties.