Raja Rammohan Roy opposed the practice of the worship of images which formed an essential feature of Hindu religion since time immemorial. He looked upon this idolatry as a degeneration from the pure monotheistic doctrine of the Hindu Scriptures. His ideas were taken up by a number of English educated persons with whose co-operation he established the 'Brahmo Samaj' in 1828.and opened his 'Church' on 23 January, 1830 before a gathering of 500 persons.He did not belong to any particular sect but organised a meeting ground for all those who discarded idolatry and worshipped one God.
A new light was thrown in the Brahmo Samaj by Keshab Chandra Sen. He introduced inter caste marriages and various other unorthodox practices which created a split of the Brahmo Samaj. 1. Adi Brahmo Samaj, 2. Brahmo Samaj of India at the end of 1866.
Keshab made some singular contributions, directly to the growth of Brahmaism and indirectly to the national life of India.He was the first to inaugurate an all India movement of religious and social reforms, by undertaking missionary tours to Bombay and Madras in 1864, and to North-West provinces four years later. he gave different names for different provinces, such as Prarthana Samaj in Bombay and Veda Samaj in Madras. This was a precursor to a similar movement which was launched by Surendra Nath Banerjee. Keshab induced the Government to pass in 1872 the Native Marriage Act, popularly known as the Civil Marriage Act, for legalising marriages which were not valid according to the Hindu Law.