The ideological surround model (ISM) of the relationship between religion and the social sciences uses innovations in standard research methods to demonstrate how the challenges of postmodern relativism can be addressed. In this project, ISM methodologies evaluated the Post-traumatic Growth Inventory-Short Form (PTGI-SF), a measure relevant to positive psychology. The PTGI-SF correlated predictably with religious variables and with psychological well-being, and such relationships also appeared with a Christian version of the PTGI-SF created through ISM empirical translation scheme procedures. In ISM comparative rationality analyses, all PTGI items proved to be ‘rational’ relative to Christian commitments, and Christian rationality assessments of these items fully or partially mediated relationships of both the psychological and Christian expressions of post-traumatic growth with other constructs. These data demonstrated how ISM methodologies can document compatibilities between the rationalities of Christianity and contemporary positive psychology and more generally can address the challenges of postmodern relativism.