A remarkable feature of India's history is that for the past several thousand years, the country has managed to not succumb to totalitarianism or to completely cave in entirety to a new power or to a new culture or new way of life - thus retaining the huge strength of diversity and pluralism.
India's has given birth to several faiths (Hinduism of so many varieties, Buddhism, Jainism, and Sikhism), and has been exposed to Christianity from 52 BC, to Zoroastrianism for over 1200 years, to Islam from very soon of the founding of that faith. India has had numerous outside influences - Greeks, Turks, Mughals, British.
Yet, the culture of plurality and resilience against totalitarianism has thrived in the multiplicity of India's religious, cultural, lingusitic diversity and in the ethos of tolerance.
This can't be said of too many places in the world - Europe quickly became fully Christian once Constantine made that the state faith, much of Latin America lost the indigenous faiths and languages and succumbed to the colonial cultures, the Middle-east shifted with each new faith, China succumbed to Communism, etc. India did not tolerate Mrs. Gandhi's Emergency, and few fringe groups have been able to take the center. India has also absorbed English without losing her languages.
Thus, the Indian approach has been one of absorption and hybridization, and toward keeping a mosaic plural culture. Today, the Hindu fanatics want to make India a "Hindurashtra", and their power is being felt. Based on India's long history and remarkable resilience, however, one can safely bet that they are unlikely to succeed, but they can create trouble - and things can be ugly. Mr. Modi needs to reign in these forces if he wants India to succeed.