Though previous research has highlighted the significant and typically positive ‘religion-health’ relationships, little attention has been paid to the psychological and social factors involved in, and resulting from absconding from religion, known as apostasy. This is despite popular culture referencing apostasy as a lonely and distressing experience. Our study qualitatively investigated the experiences and perceptions of those undergoing religious belief change and whether this made participants more vulnerable to poorer mental health. Using grounded theory and semi-structured interviews, we explored these experiences in 13 members of the UK-based Association of Black Humanists, including how they arrived at their belief change and how they felt that this may have impacted their social relationships. Thematic analysis determined a dynamic interaction between perceived predisposing factors, triggers and maintenance. Furthermore, the data suggest the relationship between apostasy and one’s sense of self and mental health to be influenced by identity crises and moderated by protective factors, such as social support. Findings are discussed against previous research and recommendations are made for future investigation.