Hindu nationalism, once a fringe ideology in India, is now mainstream. Nobody has done more to advance this cause than Prime Minister Narendra Modi, one of India’s most beloved and polarizing political leaders.

And no entity has had more influence on his political philosophy and ambitions than a paramilitary, right-wing group founded nearly a century ago and known as the RSS.

“We never imagined that we would get power in such a way,” said Ambalal Koshti, 76, who says he first brought Modi into the political wing of the Rashtriya Swayamsevak Sangh in the late 1960s in their home state, Gujarat.