New England Transcendentalism developed in part out of American Unitarianism, which was well established by 1825. It drew, in particular, upon the "liberal Christianity" of Dr. William Ellery Channing. Unitarianism spread from Massachusetts throughout New England, from church to church, primarily as dissatisfied members of Congregational parishes separated from conservative, Calvinistic parent churches. American Unitarianism had British and European antecedents traceable back to the Reformation.
Dr. Channing — described by Emerson in his "Historic Notes of Life and Letters in New England" as "one of those men who vindicate the power of the American race to produce greatness" — was the recognized leader of American Unitarianism. He proclaimed the major beliefs of the faith in 1819 in "Unitarian Christianity," a sermon delivered in Baltimore at the ordination of Jared Sparks. In 1820, Channing organized the Berry Street Conference, out of which the American Unitarian Association was established in 1825. In formulating his liberal Christianity, Channing looked to the Scriptures and to his own understanding, not to dogma handed down by preceding generations.
.Strictly speaking, the term Unitarian refers to the belief that God is one being instead of the Trinity of Father, Son, and Holy Spirit. (The Congregational parishes from which Unitarian churches broke off in the nineteenth century were Trinitarian.) New England Unitarianism, however, represented more than a rejection of the doctrine of the Trinity. It encompassed a range of liberal ideas. The Unitarians believed in God's goodness and loving kindness, in man's likeness to and ability to comprehend God, and in the human capacity for spiritual, moral, and intellectual improvement. In his "Unitarian Christianity," Channing had declared, "The idea of God, sublime . . . as it is, is the idea of our own spiritual nature, purified and enlarged to infinity. In ourselves are the elements of the Divinity." Self-culture was the means of understanding God and of bringing the individual closer to God's perfection. This idea contrasted sharply with the Calvinistic concept of innate depravity. The Unitarians also denied the notion of predestination, accepting instead free will and personal responsibility. They believed simultaneously and inconsistently in the rationality of faith and in revelation as presented in the Bible, particularly in the New Testament miracles. They reconciled this inconsistency by asserting that rationality itself was a form of revelation.
The Unitarian point of view was promulgated through several periodicals: The Christian Examiner was established in 1813, The Christian Register in 1821, The Western Messenger (a periodical of Transcendental as well as Unitarian thought) in 1835.
Through the example of Dr. Channing, Unitarianism was associated with social reform. Channing spoke and wrote about the immorality of slavery, about the cause of peace, about temperance, labor issues, and public education. In this, as in his religious faith, he influenced the Transcendentalists of the following generation. He also devoted attention to literary subjects, foreshadowing the Transcendentalists in his sense of the urgency of creating a national literature.
Emerson and others among the Transcendentalists found much to admire in Channing's liberal Christianity. Channing's concept of "likeness to God" was incorporated into Transcendental philosophy as it evolved. But they could not accept Channing's sense of how to understand this likeness. Channing had declared in his "Unitarian Christianity" sermon:
It [likeness to God] has its foundation in the original and essential capacities of the mind. In proportion as these are unfolded by right and vigorous exertion, it is extended and brightened. In proportion as these lie dormant, it is obscured. In proportion as they are perverted and overpowered by the appetites and passions, it is blotted out.
The notion here set forth owed much to the rationalism of Enlightenment philosopher John Locke. But the Transcendentalists responded to other influences besides rational Unitarianism, in particular to Kant's theory of the intuitive, mysterious, spontaneous nature of knowledge.
Other aspects of Unitarianism also failed to satisfy the needs of the Transcendentalists. As Emerson and others began careers in the ministry, it seemed to them that far too much of what was termed religion consisted solely of adherence to forms, doctrines, and literal interpretation of the Scriptures. Emerson decried the spiritual impoverishment of the "corpse-cold Unitarianism of Brattle Street and Harvard College." Minister at the Second Church in Boston, Emerson publicly rejected the practice of the Lord's Supper in 1832 and left his pastorate. Theodore Parker, in his 1841 "Discourse of the Transient and Permanent in Christianity" wrote, "It must be confessed, though with sorrow, that transient things form a great part of what is commonly taught as religion. An undue place has often been assigned to forms and doctrines, while too little stress has been laid on the divine life of the soul. . . ." Moreover, the New Testament miracles that the Unitarians had embraced as evidence of revelation became the subject of heated controversy. Emerson stated in his "Divinity School Address" (1838), "But the word Miracle, as pronounced by Christian churches, gives a false impression; it is Monster. It is not one with the blowing clover and the falling rain."
The Transcendental concept of truth was not based on the trappings of religion, which even relatively progressive Unitarian Christianity displayed. The Transcendentalists possessed a Platonic sense of the divine, independent of the changeable externals of religious practice. An individual's relationship with the kind of God the Transcendentalists envisioned could be achieved intuitively, without any connection to formal religion. This was a leveling notion, conferring authority upon the individual rather than upon those within the hierarchy of the church, elevating man from the position of passive recipient of divine truth as defined by the system and elucidated by the preacher. Channing's Unitarianism promoted liberal theology; Transcendentalism offered radical theology.