They say "anti-nationalist" is a bad thing? Wow.
Patriotism is love for one’s country. Nationalism is the belief that one’s country (and often ethnic subset) is supreme (and more deserving of prosperity), speaking generally.
Trump’s campaign rhetoric is emblematic of nationalist themes. Anti immigrant. Playing up cultural mythos. Bragging about military capabilities. Blaming foreign nations for most problems. Implying that a return to core values will bring greatness. Lots of fear and anger.
Tends to be very effective for groups of people that used to be powerful but are no longer.
If that's too much recursion, consider the World War I and II (among many others), both being based essentially in nationalism.
By my estimation India is an empire, and nationalism makes no sense in its context. Patriotism maybe, or political loyalty.
Just seems like a weird choice of political propaganda. I do understand there's a strong anti-Muslim attitude in India, which might be what they're calling nationalism. But it doesn't seem right.
The core of Hinduism remains the vedas, gita, the puranas and the upanishads. They lay out a very deep philosophy that theologians much more educated than I am have been investigating for centuries. It is a highly rigid system at its core (contrary to the freewheeling morass image Indians themselves have projected to appear non religious).
This is why India is a nation. From the tip of Jammu till the edge of Kanyakumari, people thought of the vedas as the progenitor scripture of all civilisation. They heard the exact same stories of the Mahabharatha and Ramayana for millennia. The fact that they were free to adapt it and retell or embellish it does not mean they broke away from the system itself or that the system emerged later than the stories did.
nation is defined as:
na•tion n. A relatively large group of people organized under a single, usually independent government; a country. n. The territory occupied by such a group of people.
That is a bad and definitely wrong definition