Functionalism has been the dominant theoretical model used in social sciences to explain the religious expression of prison inmates. However, not all their religious behaviours can be explained by one single paradigm. The objective of this research is to understand the complexity of religiousness in prison and present the need for new interpretative approaches that encompass the polyhedric nature of this phenomenon. The methodology applied is hermeneutic and qualitative. Two modules from the same prison were selected and a focus group was formed for each module. The focus group sessions revolved around the inmates’ religious beliefs, attitudes, and practices and how they are manifested within the prison context. The results demonstrate the functionality of religiousness in prison as an effective mechanism for adapting to a highly stressful medium and for alleviating the destructuring effects of the prison regime. The application of a constructivist hermeneutic approach as a complement to functionalism also highlighted a new type of religious expression that springs from the prison subculture, namely ‘prisonized religiousness’, a concept defined as a transcendental spiritual revival of subjective revitalization which enables inmates to create a new identity.