Lal Behari Dey was born on 18 December 1824 to a Subar?a-banik caste family at Sonapalasi near Bardhaman. After primary education in the village school he came to Calcutta with his father and was admitted to Reverend Alexander Duff's General Assembly Institution, where he studied from 1834 to 1844. (Duff's Institution is now the Scottish Church Collegiate School; he was one of the first five boys admitted by Duff/Scottish Church College.)[clarification needed] Under Duff's tutelage he formally embraced Christianity on 2 July 1843. In 1842, a year before his baptism he had published a tract, The Falsity of the Hindu Religion, which had won a prize for the best essay from a local Christian society.
From 1855 to 1867 Lal Behari was a missionary and minister of the Free Church of Scotland.
From 1867 to 1889 he worked as professor of English in Government-administered colleges at Berhampore and Hooghly. After having served in several churches in the prime of his career, he joined the Berhampore Collegiate School as Principal in 1867. Later he became Professor of English and Mental and Moral Philosophy in Hooghly Mohsin College of the University of Calcutta and stayed with it from 1872 to 1888. Being a devout Christian but pro-British Raj, he protested against any discrimination practised by the ruling class against the natives.