African-American women report higher levels of chronic conditions and church attendance relative to the overall US population. Therefore, efforts have increased over the past decade to design church-based health promotion programs. The present study compared changes in religiosity, religious social support and general social support across time within a church-based physical activity study. In a clustered randomized controlled trial, 31 churches and ~15 African-American women per church were recruited to participate. Churches were randomized to one of three 10-month programs to promote physical activity: faith-integrated (FI), non-faith integrated (NFI) or self-guided control program (C). Comparisons were made between baseline and 10-month time points to assess differences over time. A significant reduction in general social support was observed across all groups. Private religious practices and religious emotional support received increases in C and FI, respectively. Prior research findings and the current study highlight difficulty in demonstrating strong, unilateral changes in religiosity, social support and health. Additional research is needed to identify more accurate measures of these concepts. Findings from the current study have implications for the role of social support in future church-based health promotion studies.