Abstract Does the experience of war increase people’s religiosity? Much evidence supports the idea that particular religious beliefs and ritual forms can galvanize social solidarity and motivate in-group cooperation, thus facilitating a wide range of cooperative behaviours including—but not limited to—peaceful resistance and collective aggression. However, little work has focused on whether violent conflict, in turn, might fuel greater religious participation. Here, we analyse survey data from 1,709 individuals in three post-conflict societies—Uganda, Sierra Leone and Tajikistan. The nature of these conflicts allows us to infer, and statistically verify, that individuals were quasirandomly afflicted with different intensities of war experience—thus potentially providing a natural experiment. We then show that those with greater exposure to these wars were more likely to participate in Christian or Muslim religious groups and rituals, even several years after the conflict. The results are robust to a wide range of control variables and statistical checks and hold even when we compare only individuals from the same communities, ethnic groups and religions.