Religious signaling and prosociality: A review of the literature

The costly signaling theory of religion states that costly religious behaviors, badges, and bans (“religious practice” for short) are signals of commitment to the ingroup and its moral code. Such signals are proposed to increase cooperation. Here we review the empirical literature, which suggests that religious actors are often perceived as especially trustworthy and may be more likely recipients of help and cooperation. The evidence does not present a clear picture regarding the actual trustworthiness nor prosocial tendencies of religious actors. Limited available evidence suggests that routine forms of religious behavior are associated with ingroup favoritism. High-cost, infrequent, highly social forms of religious practice are associated with an increase in religious identity, but also an expanded social identity and greater tolerance for outgroup members. Following the literature review, we provide a discussion of proposed future research directions pertaining to the costs and benefits of religious practice, moderators, secular versus religious practice, and mediation of the relationship between observed religious practice and perceptions of religious actors' trustworthiness.