Syncretism between Islam and Hindusim took place IRL in at least three instances:
- you really have a lot of occurrences of syncretic popular beliefs, where shrines and even gurus/sufis are worshipped equally by Hindus and Muslims in a relatively organic/harmonious fashion, in areas with mixed populations. See
this article for example. In LI terms, this would be a religion of Indian civilization / Local variation / Traditional soul / Muslim ascendant. It could emerge in game if Muslims rule over Hindu provinces...
- then one may want to try again, and succeed, in creating and imposing the
Din-e Ilahi, a model of Statist syncretic faith representing exactly an attempt to merge Islam and Hindusim. In game terms it would be Muslim civilization / Local variation / Statist / Indian ascendant.
- Finally Sikhs comes as another example as far as they can be considered as a more elaborate version of the popular syncretism.
(BTW Bahaism being a syncretism of 19th century French enlightenment and Persian mysticism would be a bit anachronic in LI but it would otherwise be Persian / Heretical / Populist / Muslim ascendant, I guess)
All this being said, in LI the emphasis should be on Zoroastrian Hindu, which Shaytana wanted to give a larger role but could not due to the map limitation, as the logical replacer of these syncretisms. Remember that Islam was imported to India more by Persians or Persianized Turks than by Arabs, as illustrated by the Northern Indian languages being so influenced by Persian (Din-e Ilahi mentioned above uses Arabic words but a Persian construction). In LI, Persians are still, to large extent, Zoroastrians of various creeds... Plus even IRL they did import Zoroastrianism to India, although as refugees rather than conquerors... with Zoroastrianism still being a
significant element of the Indian religious scene even today, especially in Gujarat and Delhi. Now of course I am aware of the LI Hellenic Hindu syncretism which I don't comment further as it is already obvious. It is already well represented with multiple variants so no need for an advocate here. That's why I want to advocate, in particular, for a rich Zoroastrian / Hindu syncretism...
By the way an interesting real-life example of this is the still open to Zoroastrian worship
Fire temple in Baku, Azerbaijan (not to mention those in India), maintained by rich Gujarati Zoroastrians since the 19th century, a bizarre occurrence...