Cognitive scientists have attributed the ubiquity of religious narratives partly to the favored recall of minimally counterintuitive concepts within those narratives. Yet, this memory bias is inconsistent, sometimes absent, and without a functional rationale. Here, we asked if MCI concepts are more fitness relevant than intuitive concepts, and if fitness relevance can explain the existence and variability of the observed memory bias. In three studies, participants rated the potential threat and potential opportunity afforded by agents with abilities that violated folk (...) psychology, physics, or biology. As in previous work, agents with MCI abilities were recalled better than those with intuitive abilities. Additionally, agents with MCI abilities were perceived as greater threats, and as providing greater opportunities, than agents with intuitive abilities, but this perceived fitness relevance only mediated the memory bias when MCI abilities were used to accomplish disproportionally consequential outcomes. Minimally counterintuitive abilities that violated folk psychology were rated more intuitive and more of an opportunity than violations of folk physics or biology, while folk physics violations were recalled best. Explanations for these effects and their relevance to the cognitive science of religion are discussed. (shrink)