Ram Mohan Roy came to the project through argument rather than through vision. He had published against image worship in Persian and in Bengali, had translated Upanishads into Bengali and English to show that the texts he regarded as authoritative taught one formless God, and had run the Atmiya Sabha from 1815 as a discussion society. The Brahmo Sabha, founded in Calcutta in August 1828, was the congregation that followed from the argument.
The trust deed of 1830 is the founding document and it is unusually specific about what may not happen in the building. No image, statue, carving, painting or picture may be admitted; no sacrifice or offering may be made; and no sermon or prayer may be delivered that reviles or disrespects any other religion or any other person's way of worship. A hall was to be open to all people, of every description and every persuasion, for the worship of the one eternal, unsearchable and immutable Being.
Roy's other campaign ran alongside it. He argued in print against sati on the ground that the Hindu scriptural authority claimed for it did not hold, and the practice was prohibited in the Bengal Presidency by regulation in 1829. He died at Bristol in 1833, and the society he founded was carried on chiefly by Debendranath Tagore, who reorganised it, gave it a covenant of membership in 1843 and ran the Tattwabodhini Sabha alongside it.