 His sermon on "Unitarian Christianity", preached at First Unitarian Church of Baltimore in 1819, at the ordination of Jared Sparks, and that at New York in 1821, made him its interpreter.The result of the "Unitarian Controversy" (1815) was a growing division in the Congregational churches, which was emphasized in 1825 by the formation of the American Unitarian Association at Boston.It was organized "to diffuse the knowledge and promote the interests of pure Christianity" and it published tracts and books, supported poor churches, sent out missionaries into every part of the country, and established new churches in nearly all the states.