This concluding chapter draws on the different studies that this book collects, dealing with missionary work and preaching in the Arab world within monotheistic religions, while engaging in a dialogue through the ethnographic fieldworks of the authors, in Tunisia and in the Arab diaspora in Sweden. They explore guidelines for a theoretical framework to think through missionary work. Thus, they underline the issues which run through different chapters of the book. In accordance with the analogies made both by religious actors and scholars of religion, the authors spin the economic metaphor in order to carve out some aspects of missionary work, such as the importance of mobility and migrations, racial differentiation, models of gendered division of labour, and general issues of hierarchies and power. Four points emerge from the chapters as key areas of overlap, offering heuristic research avenues for a comparative anthropology of the missionary phenomenon: 1) a comparative sociology of missionary work; 2) an analysis of missionary geographies and the associated spatial metaphors; 3) the question of mobility in missionary activity, a condition engendering anonymity and distrust and serving to cast suspicion over the authenticity of conversions; 4) finally, a path focused on interpreting missionary activity through the prism of gift, exchange and debt.