For seven decades, India has been held together by its constitution, which promises equality to all. But Narendra Modi’s BJP is remaking the nation into one where some people count as more Indian than others. By Samanth Subramanian

Soon after the violence began, on 5 January, Aamir was standing outside a residence hall in Jawaharlal Nehru University in south Delhi. Aamir, a PhD student, is Muslim, and he asked to be identified only by his first name. He had come to return a book to a classmate when he saw 50 or 60 people approaching the building. They carried metal rods, cricket bats and rocks. One swung a sledgehammer. They were yelling slogans: “Shoot the traitors to the nation!” was a common one. Later, Aamir learned that they had spent the previous half-hour assaulting a gathering of teachers and students down the road. Their faces were masked, but some were still recognisable as members of a Hindu nationalist student group that has become increasingly powerful over the past few years.

The group, the Akhil Bharatiya Vidya Parishad (ABVP), is the youth wing of the Rashtriya Swayamsevak Sangh (RSS). Founded 94 years ago by men who were besotted with Mussolini’s fascists, the RSS is the holding company of Hindu supremacism: of Hindutva, as it’s called. Given its role and its size, it is difficult to find an analogue for the RSS anywhere in the world. In nearly every faith, the source of conservative theology is its hierarchical, centrally organised clergy; that theology is recast into a project of religious statecraft elsewhere, by other parties. Hinduism, though, has no principal church, no single pontiff, nobody to ordain or rule. The RSS has appointed itself as both the arbiter of theological meaning and the architect of a Hindu nation-state. It has at least 4 million volunteers, who swear oaths of allegiance and take part in quasi-military drills.