This project examines sources of variation among the wide array of individuals who describe themselves as ‘atheist.’ Broadly speaking, I hypothesize the continuing influence of factors such as childhood religiosity, time-period, and organizational affiliation explain a portion of the variation between atheists. A mixed-method analysis drew a sample of atheists raised in religion, utilizing recruitment flyers throughout Chicagoland and neighboring states. 201 online surveys and fifty semi-structured interviews polled respondents about their religious upbringings, experiences questioning and leaving religion, and current stances and definitions surrounding atheism. Analysis finds religious intensity in respondents’ upbringings exerts influence over the misgivings they experienced with their childhood religion, eventually culminating in exit from theism. Childhood religious intensity also exerts direct and indirect influence on present-day beliefs: specific mentions of residual, dogmatism, and one’s symbolic boundaries around atheism. Respondents’ decision to affiliate with an atheist group stemmed from zealotry and earlier social networks, though precise motivations differ widely between atheists, and may change over one’s lifetime. Finally, there is a cohort effect in how atheists wish to engage religion: early cohorts stress a battle centered around rights, while later cohorts focus on stewardship and human progress. Overall, these findings yield support for residual effects from one’s childhood religion, as well as influence from the broader social and political climate outside one’s household and previous community of worship. The study also lays the groundwork for future research, cataloguing a spectrum of variation in definitions of atheism and epistemological stances concerning the (non)existence of god.