Religion may be an important source of altruism, yet from a scientific perspective, religion’s effects on thought and behavior are not well understood. By combining perspectives from the psychology and cognitive science of religion with the framework of gene–environment interactions, this research aims to answer basic questions about religion in novel ways. In order to investigate biological and cognitive explanations for religiously motivated altruism, I will utilize perspectives from psychology and cognitive science (i.e., examining potential cognitive mediators) and techniques from genetics (i.e., measuring predisposition to reward and punishment sensitivity using a multilocus genetic composite of dopamine-related genes) while also considering the social environment (i.e., deservingness of the target of altruism) in a gene–environment interaction. Across three experiments, this research will examine: 1) whether cognitive mediators, such as concerns about supernatural punishment or reward, explain the effect of religion on altruism, and 2) whether concerns about supernatural punishment and reward affect altruism differently depending on genetic predispositions to be reward- and punishment-sensitive and also depending on the social context. This research will test a proposed model for how both biological and cognitive perspectives can be integrated to understand why religion increases altruism for certain individuals in particular contexts. There are a number of key outputs and outcomes of this research, such as developing theory and shaping future research via publications and presentations. Importantly, it will have the enduring impact of forming a foundation for scientists to study religion with multiple theoretical and methodological perspectives to understand the processes surrounding the phenomenon at a deeper level.