Monotheistic movement within Hinduism , founded in Calcutta (now Kolkata) in 1828 by Ram Mohun Roy .
It rejected the authority of the Vedas and the doctrine of avatars , did not insist on belief in karma or rebirth, denounced polytheism and the caste system, and adopted some Christian practices. Roy's intention was to reform Hinduism from within, but his successor, Debendranath Tagore , rejected Vedic authority. In 1866 Keshab Chunder Sen organized the more radical Brahmo Samaj of India, which campaigned for the education of women and against child marriages. After Keshab nonetheless arranged a marriage for his underage daughter, a third group, Sadharan Brahmo Samaj, was formed in 1878. It gradually reverted to the teaching of the Upanishads but continued the work of social reform. The movement, always an elite group without significant popular following, lost force in the 20th century.