Prashant Keshavmurthy in The Wire:
For over a thousand years, since around the ninth century, the imagination of the Indian in Arabic and Persian literature coalesced in the figure of a non-Islamic religious specialist, the Brahman. Not that of the Kayastha Hindu, the men of whose caste, from the mid-16th century onward, increasingly staffed the bureaucracies of the Afghan and Mughal states of North India, nor that of the occasional Brahman who, by familial and personal circumstance, received a traditional madrasa education in Arabic and Persian. For both these types of men were so steeped in Persian-Islamic learning and comportment as to be Muslim, in an elite cultural sense.
Rather, the Brahman of the Persian literary imagination was continuous with the Brahman of the earliest texts of kalāmor rational theology in Arabic, whether Muslim or Jewish. This Brahman was purely a debate opponent invoked by Muslim and Jewish theologians to defend the necessity of prophecy. These heresiarchs presented him as a proponent of the sufficiency of human reason and thus of the redundancy of prophets. Sarah Stroumsa, a scholar of early Islamic-Jewish theology, has argued that early Muslim-Jewish theological debates were shaped by encounters with Brahmans and that these debates were conducted solely on the shared ground of logic, avoiding reference to theological doctrines specific to each side. The polemically simplified picture of the Brahman this left behind in the archive of early Muslim-Jewish heresiography was perhaps what allowed him to pass from theology into literature, where he congealed into a stock character.
More here.