Evolutionary definitions of altruism are only concerned with reproductive consequences and not motives or other psychological mechanisms, making them ideal for generalization to all forms of organisms. Hamilton’s inclusive fitness theory explains altruistic behavior toward genetic relatives and has generated extensive empirical support. Trivers’ theory of reciprocal altruism helps explain patterns of helping among non-kin, and other research has demonstrated that human helping intentions follow fitness consequences from age-based reproductive value on altruism. The current study examines a novel psychological factor, belief in the afterlife, which may influence altruistic helping intentions. Belief in the afterlife was incorporated into a previous study design assessing the effects of a target’s genetic relatedness and age-based reproductive value. The influences of inclusive fitness and target age were reproduced in a non-Western sample of participants (N = 300) in Iran. Belief in the afterlife predicted the overall confidence of risking one’s life to save another across all targets, and also moderated the effects of genetic relatedness and target age. Rather than promoting altruism equitably or advantaging those favored by adaptive tendencies, higher belief in an afterlife aligned with these tendencies in promoting further favoritism toward close kin and younger targets with higher reproductive value.