Why do people stop identifying as religious—and how does this religious deidentification affect their thoughts, feelings, and actions? The percentage of religious “nones” is steadily increasing in the United States (and globally), and some of these people were at one time religious, but no longer affiliate with religion (or perhaps even hold religious beliefs). Given this steady increase, it is important to understand what may motivate some individuals to shift away from their religious identity. Moreover, it is both theoretically and practically important to determine whether the psychological experiences of formerly religious individuals more closely resemble currently religious or never religious individuals. Existing research on religious disbelief has lacked precise theorizing and measurement to parse apart the never religious from the formerly religious—individuals who at one time, but no longer, identify as religious. The proposed research fills this gap by exploring the nature and consequences of religious deidentification. Our research will accomplish three principal aims. First, we seek to obtain nationally representative samples across various cultures to understand the prevalence and features of deidentification. Second, we will compare presently religious, formerly religious, and never religious individuals across a series of dimensions, including religious cognitions, god-concepts, moral cognition and judgment, motivations, emotions, and psychological well-being measures. Third, these data will set-up for a larger study to explore how many people re-identify as religious (i.e., what are the factors for reidentification?). This proposal includes a set of nationally representative samples across religiously diverse countries (USA, Netherlands, Hong Kong) and a suite of experimental studies that will yield high-impact publications intended to catalyze a new field of inquiry on religious deconversion, and set up future work on religious reidentification.