Smyth, Thomas. The fundamental Doctrines of Christianity, the true and only required Basis of Charity and Christian Effort; A Discourse, delivered at Philadelphia, on the Twenty-second Anniversary of the American Sunday-School Union, May 17, 1846. Philadelphia: American Sunday-School Union, 1846. First Edition. 
Stab-sewn pamphlet with white printed wrappers, wrappers now dark, some soil & stains, slight tattering to edges, 4 1/2 x 7 inches, 39 clean pp., top right corner dog-eared.
"Voluntary associations" - Christians from different denominations working together for a common cause, e.g. Sunday Schools - were a point of controversy at this time. Some believed that they were guilty of dulling their distinctives to work with Christians who would not have been allowed to join their church, (a Methodist could not join a Presbyterian church and remain Methodist, for instance). In this discourse, Smyth argues that the fundamentals of Christianity are enough to allow members of different orthodox Protestant churches to work together for the cause of Christ. He says that the science or theology of salvation which leads to particular denominational beliefs are not the fundamentals, and need not be of concern to evangelical Christians of different denominations.
Thomas Smyth, D.D. (1808-1873), born at Belfast, Ireland, educated at Queen’s College, Belfast, in London, and at Princeton Theological Seminary. He was pastor of the Second Presbyterian Church of Charleston, South Carolina, from 1832 to until his death in 1873.
"Smyth moved in a circle of conservative Presbyterian scholars that included Charles Hodge and Archibald Alexander of Princeton and James Henley Thornwell and George Howe of the Presbyterian Theological Seminary in Columbia. Their theological and social perspectives were deeply influenced by Protestant Scholasticism, the philosophical school of Scottish Common Sense Realism, and their social location in the midst of conservative and affluent elements of American society. They sought to avoid extremes in theology, ethics, and politics, believing that extremes led to disorder in thought and life.
"Smyth was a great collector of books and made trips to Great Britain seeking rare volumes, especially those connected with the history of Calvinism. His personal library numbered almost twenty thousand volumes, most of which he eventually sold to Columbia Theological Seminary. Smyth was a compulsive writer, and the ten volumes of his Collected Works showed him to be a person of wide interests but not the deep learning of Thornwell or Hodge. For his studies in church history he received an honorary doctor of divinity from the College of New Jersey (Princeton). Perhaps his most important book was The Unity of the Human Races, in which he defended the full humanity of Africans and the sophistication of their past civilizations. In this study he attacked the claims of Louis Agassiz and southern radicals who were arguing that physiologically whites and blacks were so different that they must have had separate origins." - Erskine Clarke, South Carolina Encyclopedia online.