Observers of early post-revolutionary Iran were surprised to witness the politically inexperienced clerical community and their dedicated lay followers succeed in the state-building process. Domestic opposition, international isolation, and economic hardship made observers sense a looming demise, to the extent that they believed the Iraqi invasion of 1980 would serve as the final blow to the nascent Islamic Republic of Iran. To claim that religious-cultural solidarity was the key to the Islamists’ unexpected organizational success is deemed an insufficient, and even shallow, explanation. I argue, however, that religion can and should be brought back as an explanatory factor to complement, if not completely replace, structural explanations. Even though religion as a systematic constellation of beliefs and rituals is not a satisfactory analytic element, religion as shared lived experience, as a source of cultural dispositions—in a Bourdieusian sense—that harmonize collective responses to social contingencies, can expand our understanding of post-revolutionary institution building in Iran. The group of activists belonging to Shia Muslim communities close to Ayatollah Khomeini demonstrated a practical cognitive disposition for instantly recognizing each other’s cultural belonging. Thereby they created instant, strong ties that amounted to flexible formations that filled the gap of meticulously structured and controlled organizations—something which they did not have managerial experience for. I lay out the characteristics of this collective work style by studying post-revolutionary institution building in 1979-80 Iran. Through in-depth interviews with activists as well as memoirs and archival documents, I demonstrate that the Islamists’ historically shared lifeworld as Shi’a Muslims provided them with the confidence to trust a fellow Muslim activist and welcome him to the group instantaneously, without recourse to explicit principles of orthodoxy or orthopraxy. Reliance on elastically strong ties created as such allowed leaders to act against collective decisions as contingencies necessitated, endowed grassroots clusters with trust and authority, and enabled consequential decisions to be made informally to avoid organizational accountability to rival institutions.