Inspired as much by interfaith dialogue as by ethnographic discussions of intersubjectivity, I draw some narrow debates within Indian Islam outside of their usual South Asianist and/or Islam-centric frameworks and also resist the academic injunction to purify boundaries between theology and anthropological analysis. I present ethnography from Kerala factional debates raising two vexed questions: authority of interpretation; and the matter of shirk or deviation from tauheed, or true monotheism. My analysis follows impulses towards, firstly, a de-exceptionalising of Islam via comparison, drawing ethnography towards a wider ‘Abrahamic’ framework, in an eccentric move of reading Islamic debates through moments in commentary on Christian traditions; and secondly, I engage recent theological moves toward performative and deconstructive readings of religion. In Muslim traditions, Quran and hadith as ultimate authority are supported by the methods of qiyas – analogy – and considerations of ijma – community consensus. From the beginning, Islam has recognised that, “The Quran does not speak with a tongue; it needs interpreters and interpreters are people” ( Esack, 1997). Performative and deconstructive understandings of religion are perhaps then already anticipated in the Islamic tradition, unlike (Western) Christianity, which has long been restrained by a narrow focus upon either scriptura or traditio – with the third pole of ‘community consensus’ hidden from sight and not often acknowledged, matters of consensus/performativity only recently becoming recognised as a proper and legitimate part of processes of interpretation, as Dalit, queer and feminist theologies emerge and come of age.