.......So we say it is fine to have caste-based political parties but not religion-based ones...
We in India still have plenty, e.g., Owaisis MIM in hyderabad is a muslim based National or rather regional party and it still prouds on that as a beholder of muslim minority rights upholder.
India is a pluralistic country and for that reason, we can have pluralistic thinking and attitudes which had generated such a wide variety of castes (castes b/c they are considered to be part of Hinduism but had it been any other religion, it would have been sectarianism such as sunni/bahai, catholic/protastants etc)b/c they don't completely accept pluralism. According to "The Survey of Hinduism" byKloss..., It was most developed and most assimilating of all religions until it came into contact with monotheistic and non-compromising religions of the western world. We have to understand Hinduism and its followers in this context.