The entanglement of religion and politics in Iran can serve as a potential source of mistrust between the anthropologist and her interlocutors (Kalinock 2004:473), particularly when the research is centered around faith-based communities and their practices. In the contested terrain of contemporary Iranian politics, the presumed intentions/agendas of the researcher are more likely to come under scrutiny before any ethnographic research touching on faith-related subjects can take place. In such circumstances where the potential for mistrust is high, the perceived position of the anthropologist as an “insider,” a “halfie,” or an “outsider” can make or break an ethnographic endeavor. In this paper, I draw on my own fieldwork with two Iranian-American faith-based communities in the US--Muslims and Christian converts--to address challenges of building trust and rapport with my interlocutors in the absence of a shared faith, despite sharing other similarities and connections. I render my observations vis-à-vis existing scholarship, building upon ethnographic studies in which the researcher and the research population do not share a belief system or political ideology (Erzen 2006, Kalinock 2004, Harning 2000, Luhrmann 2004, 2012), and the literature on the dynamics of occupying the halfie position in the field (Abu-Lughod 1991; Behar 1996; Narayan 1993). Drawing from and combining both strains of scholarship, I address faith/belief-related positionality as part of researcher’s “multiplex subjectivity” (Rosaldo 1989) which is highlighted in the halfie situation, and the challenges it can pose for navigating the dynamics of trust and ethics in ethnography. While halfie anthropologists may have easier access to their research population by virtue of pre-existing national, ethnic, or linguistic connections, I argue that being a halfie in faith-based Iranian communities (particularly in diaspora) can increase the potential for mistrust. In other words, if not considered an “insider” of the faith, being a “halfie” in other respects does not necessarily ease the establishment of rapport and may even become a liability, as openness about one’s faith-related positionality might bar researcher’s access to the group. In this regard, and based on my own fieldwork with Iranian-American communities, I address whether it is “ethical” ethnographic practice for the halfie anthropologist to take on the position of an “insider” through “performing” faith; i.e. by participant observation in groups’ faith-related activities, or by simply allowing the group to interpret her participation as a sign of affinity and/or propensity towards their religious beliefs.