Through ethnographic research, Killian examines vitality in Philadelphia and Berea, two Christian Intentional Communities whose participants live in close proximity with one another to achieve religious values. Pulling from Anthony Giddens' theory of structuration, Killian argues that the vitality of both communities cannot be reduced to deterministic structural, individual, or organizational causes. Rather, vitality in these communities is affected by all of these causes in relationship to one another. In other words, it's not that each explanation "matters" (e.g., social structures matter, organizational behaviors matter, individual religious choices matter), but that these explanations matter to each other (e.g., social structures matter to individual choices, individual choices matter to organizational behaviors, and social structures matter to organizational choices, etc.). To make this argument, Killian develops the idea of the vitality nexus—the interconnected relationship between the various explanations of religious vitality.