In this article, I analyze the religiosity of Bompietro of Bologna as reported in the register of the inquisition of Bologna, 1291-1310. I attempt to show that Bompietro's religiosity was above all practical; its doctrinal content seems to be scarce, and it was not focused on support of any church (Roman or Cathar). Bompietro's case reveals a non-confessional type of religiosity, one still underrepresented in the image of medieval Christianity. This case also encourages wider reflection on the relations between beliefs, practices and membership. Far from having direct causal links, these relations can sometimes prove quite intricate.