Childhood adversity is associated with lifelong health problems, with chronic inflammation identified as a key mechanism of biological embedding. Religion and spirituality (R/S) may buffer the adverse effects of early trauma, particularly among adult religious converts who may demonstrate heightened engagement ("zeal of the convert" phenomenon). However, limited research has examined R/S moderation using objective biological outcomes or investigated differential effects by conversion status. This cross-sectional study examined the relationship between adverse childhood experiences (ACEs) and adult inflammation, testing whether R/S engagement moderates this relationship and whether moderation effects differ by religious conversion status. Secondary data analysis utilized the Midlife in the United States (MIDUS) 2 Biomarker Project (N = 374 midlife adults). Measures included ACEs (7-item retrospective report), inflammatory biomarkers (interleukin-6, C-reactive protein, tumor necrosis factor-alpha), R/S engagement (religious service attendance, Daily Spiritual Experiences Scale), and religious conversion (childhood-to-adult affiliation change). Hierarchical regression and moderation analyses controlled for demographic, health, and lifestyle factors. Contrary to hypotheses, no significant main effects of ACEs on inflammation emerged, and R/S engagement did not significantly moderate the ACE-inflammation relationship. A marginal trend was observed for TNF-α (p = .08). Null findings suggest substantial complexity in ACE-inflammation pathways and highlight methodological challenges including cross-sectional design, missing data, survivor bias, and R/S measurement limitations. Future research requires longitudinal designs, comprehensive R/S assessment, and refined biopsychospiritual models. Despite null results, this study provides a rigorous test of theoretical predictions using objective biomarkers and offers important guidance for advancing biopsychospiritual science. Keywords: childhood adversity, inflammation, religious conversion, spirituality, post-traumatic growth