What was the ideological foundation of the growth of Extremism (militant nationalism)?

It has been rightly pointed out by Professor Amales Tripathy that the preachings of Bankimchandra Chatterjee, Swami Vivekananda, Dayananda Saraswati, etc. constituted the ideological background of the rise of Extremism.

Though none of them was a politician, yet their teachings and writings served as an inspiration for developing militant spirit among the Indian youths.

This may be illustrated by examples. The militancy of the Santan Dal in the novel Ancmdamcith written by Bankimchandra instilled among the Indians a true love for the country.

The call Vivekananda had given to the young generation had in it the seeds of Extremism Vivekananda laid emphasis on gathering of strength by the youths for driving the British out of the country.

Sister Nivedita tried her level best to translate into action the teachings of Vivekananda regarding nationalism in India.

Nivedita placed freedom as the primary objective of life in India. Thus all those mentioned above laid the ideological background of the rise of militant nationalism in Indian politics.