Religious costly signal induces more trustworthiness than secular costly signal: A study of pilgrimage to Santiago de Compostela

Research suggests that costly displays of commitment increase trust and cooperation. In five studies (total n > 1,700), we investigated whether costly behaviours are more effective in promoting trust when integrated within a religious rather than secular context using the pilgrimage to Santiago de Compostela as a costly display of commitment. First, we show that pilgrims base their pilgrim identity on physical effort (Studies 1A and 1B). Next, in three pre‐registered experiments (Studies 2–4) with the Spanish population, we compared the trustworthiness of people posting on Facebook about their participation in a religious pilgrimage and a secular pilgrimage/hike with various control posts. The results showed that pilgrims/hikers are perceived as more trustworthy than non‐pilgrims and that long‐distance pilgrims are perceived as more trustworthy than short‐distance pilgrims. Moreover, these effects are stronger when the pilgrimage is framed in a religious context compared to a secular context. Our research highlights the key role of religion in the costly signalling of commitment.