The cognitive science of religions’ By-Product Theory contends that much religious thought and behavior can be explained in terms of the cultural activation of maturationally natural cognitive systems. Those systems address fundamental problems of human survival, encompassing such capacities as hazard precautions, agency detection, language processing, and theory of mind. Across cultures they typically arise effortlessly and unconsciously during early childhood. They are not taught and appear independent of general intelligence. Theory of mind (mentalizing) undergirds an instantaneous and automatic intuitive understanding of minds, mental representations, and their implications for agents’ actions. By-Product theorists hypothesize about a social cognition content bias, holding that mentalizing capacities inform participants’ implicit understanding of religious representations of agents with counter-intuitive properties. That hypothesis, in combination with Baron-Cohen’s account of Autistic Spectrum Disorder (ASD) in terms of diminished theory of mind capacities (what he calls “mind-blindness”), suggests an impaired religious understanding hypothesis. It proposes that people with ASD have substantial limitations in intuitive understanding of and creative inferences from such representations. Norenzayan argues for a mind-blind atheism hypothesis, which asserts that the truth of these first two hypotheses suggests that people with ASD have an increased probability, compared to the general population, of being atheists. Numerous empirical studies have explored these three hypotheses’ merits. After carefully pondering distinctions between intuitive versus reflective mentalizing and between explicit versus implicit measures and affective versus cognitive measures of mentalizing, the available empirical evidence provides substantial support for the first two hypotheses and non-trivial support for the third.