Most of the Society's founding members and leadership were members of Belfast's first three Presbyterian churches, all in Rosemary Street. The obstetrician William Drennan, who first proposed the society, was the son of the minister of the First Church; Samuel Neilson, owner of the largest woollen warehouse in Belfast, was in the Second Church; Henry Joy McCracken, born into the town's leading fortunes in shipping and linen-manufacture, was a Third Church member. Despite theological differences (the First and Second Churches did not subscribe to the Westminster Confession of Faith), the Rosemary Street churches were of a broadly "New Light" persuasion. Educated at the University of Glasgow, their elected ministers inclined in their teaching toward conscience and "the light of nature" rather than doctrine.