Bhaktisiddhanta Sarasvati Goswami (Bhaktisiddhanta Sarasvati Gosvami; Bengali: ?????????????? ???????; Bengali: [b??ktisidd?anto ??r??b?ti] (listen); 6 February 1874 – 1 January 1937), born Bimla Prasad Datt (Bimala Prasada Datta, Bengali: [bimola pr???d d?tto]), was a Gaudiya Vaisnava Hindu guru (spiritual master), acarya (philosophy instructor), and revivalist in early 20th century northeastern India.
Bimla Prasad was born in 1874 in Puri (Orissa) a son of Kedarnath Datta Bhaktivinoda Thakur, a recognised Bengali Gaudiya Vaishnava philosopher and teacher.
Bimla Prasad received both Western and traditional Indian education and gradually established himself as a leading intellectual among the bhadralok (Western-educated and often Hindu Bengali residents of colonial Calcutta), earning the title Siddhanta Sarasvati ("the pinnacle of wisdom").
Under the direction of his father and spiritual preceptor, Bimla Prasad took initiation (diksha) into Gaudiya Vaishnavism from the Vaishnava ascetic Gaurkishor Das Babaji, receiving the name Varshabhanavi-devi-dayita Dasa (Var?abhanavi-devi-dayita Dasa), "servant of Krishna, the beloved of Radha"), and dedicated himself to arduous ascetic discipline, recitation of the Hare Krishna mantra on beads (japa), and study of classical Vaishnava literature.
After the deaths of his father and his guru, in 1918 Bimla Prasad accepted the Hindu formal order of asceticism (sannyasa), becoming known as Bhaktisiddhanta Saraswati Goswami.
In the same year Bhaktisiddhanta Saraswati inaugurated in Calcutta the first center of his institution, later known as the Gaudiya Math.
It soon developed into a dynamic missionary and educational institution with sixty-four branches across India and three centres abroad (in Burma, Germany, and England).
The Math propagated the teachings of Gaudiya Vaishnavism by means of daily, weekly, and monthly periodicals, books of the Vaishnava canon, and public programs as well as through such innovations as "theistic exhibitions" with dioramas.
Known for his intense and outspoken oratory and writing style as the "acharya-keshari" ("lion guru").
Bhaktisiddhanta opposed the monistic interpretation of Hinduism, or advaita, that had emerged as the prevalent strand of Hindu thought in India, seeking to establish traditional personalist krishna-bhakti as its fulfillment and higher synthesis.
At the same time, through lecturing and writing, Bhaktisiddhanta Saraswati (Prabhupad) targeted both the ritualistic casteism of smarta brahmanas and sensualised practices of numerous Gaudiya Vaishnavism spin-offs, branding them as apasampradayas – deviations from the original Gaudiya Vaishnavism taught in the 16th century by Caitanya Mahaprabhu and his close successors.
The mission initiated by Bhaktivinoda and developed by Bhaktisiddhanta emerged as "the most powerful reformist movement" of Vaishnavism in Bengal of the 19th and early 20th century.
However, after the demise of Bhaktisiddhanta Saraswati Goswami Prabhupad in 1937, the Gaudiya Math became tangled by internal dissent, and the united mission in India was effectively fragmented.
Over decades, the movement regained its momentum.
In 1966 its offshoot, the International Society for Krishna Consciousness (ISKCON), was founded by Bhaktisiddhanta's disciple Bhaktivedanta Swami in New York City and spearheaded the spread of Gaudiya Vaisnava teachings and practice globally.
The Bhaktisiddhanta's branch of Gaudiya Vaishnavism presently counts over 500,000 adherents worldwide, with its public profile far exceeding the size of its constituency.