This article offers an affirmative construal of atheism: the attempt to make sense of the world with naturalist explanations and to act sensibly in society following secularist principles (i.e., without relying on supernatural agents or complying with supernatural authorities). After briefly describing the conceptual framework behind this positive conception of a nonreligious worldview, we outline the construction and present the findings of two computational models that simulate some of the cognitive and coalitional mechanisms that engender and nurture religious and nonreligious worldviews. These models allow us to explore the causal dynamics within complex adaptive systems involving (dis)belief in supernatural agents and (dis)affiliation from religious institutions. (PsycINFO Database Record (c) 2018 APA, all rights reserved)