Studying the overlaps between religion and politics in human geography is no longer a niche pursuit. Now, a plethora of literature in the discipline covers various facets of the topic, analysing the role of religion in contexts ranging from welfare contracts to geopolitical imaginations. Furthermore, investigating the religion/politics interface has been enhanced in recent years by increasing theoretical innovation in religious geography, incorporating poststructural epistemologies into the subdiscipline. This shift has directed geographers to the fluid construction of practices and places through the everyday lives of religious subjects and communities. Despite these developments, I argue that studies at the religion/politics interface still lack an epistemology that can adequately comprehend emerging empirical work in geography and associated disciplines that highlights the blurring of religious praxis into activism. Geographers have rarely represented the mechanisms that produce the heterogeneity of religious involvement in politics, putting the new poststructural epistemologies in the subdiscipline to work by categorising religious subjects and communities as homogeneously progressive or regressive, or focussing instead on the affective atmospheres and internal dynamics of faith communities. In this thesis I argue that in order to understand religious involvement in activism, geographers of religion need to begin to blend poststructural epistemologies that attend to the everyday fluidity of religion with epistemological work on networks in activist geographies. This is necessary work because these two realms are beginning to intermingle on the ground, consequently highlighting the production of religious subjectivities between religious and activist practices. In response to this gap between theory and empirics, I turn my attention to faith communities that embody elements of a postchristendom ethos, flattening religious hierarchies, welcoming difference, and engaging beyond themselves through social justice activism. By addressing this context I can underscore the knowledges that geographies of the religion/politics interface have missed so far, examining the multiple factors at play in the formation of faith community raison d’êtres, the accommodation of difference in faith communities, and how religious subjects negotiate their praxis between religious and activist spaces. By drawing attention to these issues and developing an epistemology to deal with them, this thesis develops more nuanced ways of producing knowledge about religious subjectivities and communities as they relate to activism.