Biblical Unitarianism encompasses the key doctrines of nontrinitarian Christians who affirm the Bible as their sole authority, and from it base their beliefs that God the Father is a singular being, the only one God, and that Jesus Christ is God’s son, but not divine. The term "biblical Unitarianism" is connected first with Robert Spears and Samuel Sharpe of the Christian Life magazine in the 1880s. It is a neologism (or retronym) that gained increasing currency in nontrinitarian literature during the 20th century as the mainstream Unitarian churches moved away from belief in the Bible and, in the United States, towards merger with Universalism. It has been used since the late 19th century by conservative Christian Unitarians, and sometimes by historians, to refer to Scripture-fundamentalist Unitarians of the 16th–18th centuries. Its use is problematic in that Unitarians from the 17th to the 20th centuries all had attachment to the Bible, but in differing ways.
A few denominations use this term to describe themselves, clarifying the distinction between them and those churches which, from the late 19th century, evolved into modern British Unitarianism and, primarily in the United States, Unitarian Universalism.
The history of Unitarianism was as a "scripturally oriented movement" which denied the Trinity and held various understandings of Jesus. Over time, however—specifically, in the mid-19th century—Unitarianism moved away from a belief in the necessity of the Bible as the source of religious truth. The nomenclature "biblical" in "biblical Unitarianism" is to identify the groups which did not make such a move.
Early Unitarians and the Bible
Historians such as George Huntston Williams (1914–2000) rarely employ the term "Biblical Unitarian", as it would be anachronistic. Those individuals and congregations that we may now think of as Unitarians went through a range of beliefs about Jesus: that he wasn't eternally pre-existent but was created by God the Father (Arianism); or that God the Father and God the Son were two distinct Gods (Binitarianism); or that he originated at the virgin birth (Socinianism); or that he was simply a godly man (Adoptionism or Psilanthropism).
For early unitarians such as Henry Hedworth, who introduced the term "Unitarian" from Holland into England in 1673, the idea that Unitarianism was "Biblical" was axiomatic, since the whole thrust of the 16th and 17th century Unitarian and Arian movements was based on sola scriptura argumentation from Scripture, as in the case of the Christological writings of Isaac Newton.
The Unitarian Churches (1774 onwards)
Theophilus Lindsey established the first avowedly Unitarian church in England in 1774 at Essex Street Chapel. Nontrinitarianism was against the law until the Doctrine of the Trinity Act 1813, but legal difficulties with the authorities were overcome with the help of barrister John Lee, who later became Attorney General. Unitarians of this time continued to consider their teachings as "Biblical", though increasingly questioning the inspiration of the Bible and the accounts of the miraculous. (See Rational Dissenters for more.) Divergence in the Unitarian Church was increasingly evident after 1800 with the majority following the rationalist views of writers such as Thomas Belsham and Richard Wright, who wrote against the miraculous conception, while a minority held to the views of traditionalists.
The Unitarian Church of Transylvania remained a conservative "Biblical" Unitarian movement largely isolated from developments in the West until the 1830s. The Summa Universae Theologiae Christianae secundum Unitarios (1787) represents a conservative position which held into the late 19th century.
The New Encyclopædia Britannica notes that the Transcendentalist movement of Ralph Waldo Emerson "shattered rationalist, biblical Unitarianism — now grown conservative — and replaced it with intuitional religion and social idealism. When Unitarianism spread to the newly opened Middle West, its religious fundamentals changed to human aspiration and scientific truth, rather than Christianity and the Bible."
First uses of the term
An early example of the term "Biblical Unitarianism" occurs in the British and Foreign Evangelical Review (1882) in an article on the "Waning of Biblical Unitarianism". In the following year, Peter William Clayden's biography of Samuel Sharpe (1883) describes him as a "Biblical Unitarian", adding, "His intensely practical mind, and his business training, joined with his great though rational reverence for the Bible, made him long for definite views expressed in scripture language."
The context of the term in the above examples relates to the tension from the 1830s onward between more traditional and relatively scripture-fundamentalist Unitarians and those advocating a freer approach such as transcendentalists Theodore Parker and James Martineau. This conflict came to a head in 1876 when Robert Spears resigned from the British and Foreign Unitarian Association and, with the support of Sharpe, a former president of the Association, began to publish a rival magazine. In this context, Sharpe is referred to again by John M. Robertson (1929) as a "Biblical Unitarian,"  and adds that Sharpes' magazine, The Christian Life, was largely aimed at combatting growing agnosticism in Unitarian pulpits. However, though Sharpe may have used the term, and later been called, "Biblical Unitarian", he did not set up any lobby group of that name within Unitarianism.
The label of "Biblical Unitarianism" is also attributed to earlier generations than Sharpe by Henry Gow (1928), who even compares this with "Channing Unitarianism", a reference to the still relatively scripture-fundamentalist views of William Ellery Channing: "... and for a time, Unitarianism became the faith of many, if not most, of the leading citizens and thinkers of New England. As in England, it was a definitely Biblical Unitarianism."
Alexander Elliott Peaston (1940) pinpoints 1862 as the year of change from "Biblical Unitarianism" to newer models in England, where formerly belief in miracles and the resurrection were dominant. The entry of higher criticism into Unitarianism via Alexander Geddes and others dealt a "blow at the biblical Unitarianism of Joseph Priestley". Walter H. Burgess (1943) adopts the same terminology — "Biblical Unitarianism" vs. "the newer Unitarianism" — to describe the tension in Wales in the 1870s between the deists David and Charles Lloyd vs. Gwilym Marles. A similar example occurs in quotation marks from historian Stange (1984).
Earl Morse Wilbur, in his monumental A History of Unitarianism (1945), does not describe any group by the terminology "Biblical Unitarian", though the tension between the fundamentalist origins of Unitarianism and post-Christian direction of late 19th century Unitarianism does begin to appear in the later volumes.
Modern use of the term
Although Spears and Sharpe made appeal to the term "Biblical Unitarianism" in The Christian life (e.g. Volume 5, 1880), an appeal to the concept of "Biblical Unitarianism" by individuals and churches is rare until after Unitarian Universalism was formed from the merger in 1961 of two historically Christian denominations, the Universalist Church of America and the American Unitarian Association. In some cases in the 1870s where the name "Unitarian" was still considered too associated with "the narrowly Biblical type of liberal theologian", other names, such as "Christian Free Church", were employed. Larsen (2011) applies Spears' "biblical Unitarian" to him in regard to his 1876 resignation.
Identification of the conservative biblical-literalist strain of Unitarianism is found also in consideration of conservative Scottish Unitarians such as George Harris, described as a supporter of "old biblical Unitarianism." (Stange, 1984).
The term "biblical Unitarian" only begins to reappear frequently in the 1990s in the writings of those associated with a revival of interest in early Unitarian figures such as Fausto Sozzini and John Biddle ("the Father of English Unitarianism"), as well as Arians like William Whiston. An example is the journal A Journal from the Radical Reformation, A Testimony to Biblical Unitarianism (1993–present).
Alongside this historical interest in the Radical Reformation, during the 1990s the term "biblical unitarian" also begins to appear in antitrinitarian publications without either 'b' or 'u' capitalized.
There may be small continuing groups of Christian Unitarians descended from the Unitarian churches who look to the works of Spears, Sharpe and earlier. However, in terms of denominations today which could be identified as "biblical unitarian", the two most visible names are the Church of God General Conference (CoGGC), with 5,000 members in the USA, and Christadelphians, with 60,000 members worldwide. Both of these groups share nontrinitarian, specifically Socinian, Christology and both have historians — Anthony Buzzard among CoGGC, the geographer Alan Eyre among Christadelphians — who have acknowledged works such as the Racovian Catechism and Biddle's Twofold Catechism as prefiguring and compatible with their beliefs.
Christadelphians are more reserved than CoGGC in association with the name "Unitarian", given that the Unitarian Church still exists in Britain and many of its independent congregations are post-Christian. Although the Christadelphians' early growth in Scotland in the 1850s was partly a result of intake of Scottish nonconformists and Free Church members including conservative Unitarians, members also came from the disaffected nontrinitarian wing of the Restoration Movement. John Thomas, founder of the Christadelphians, was equally unsympathetic to Trinitarians and Unitarians, saying that an exposition of scripture clears away a lot of 'rubbish' from discussion on the Godhead and delivers a 'quietus' to Trinitarianism and Unitarianism.
In his overview of 'Biblical monotheism today', along with Christadelphians and the CoGGC Professor Rob J. Hyndman lists the Church of God of the Abrahamic Faith (aka Church of the Blessed Hope), The Way International, Spirit and Truth Fellowship International, Living Hope International Ministries, and Christian Disciples Church as current "Biblical monotheistic groups". He also recognises "scattered congregations meeting independently who are unaffiliated with any denomination or para-church organization", but who might interact via networks like the Worldwide Scattered Brethren Network and the Association for Christian Development.
Another small group is the Chiesa Cristiana in Italia, a breakaway from the Assemblies of God. The Seventh Day Anabaptists are another small group based out of Los Angeles, CA., formed by Solomon Rodriguez in 2017, that hold to Biblical Unitarian beliefs 
- Conway Hall Ethical Society
- Newington Green Unitarian Church
- Unitarian Christian Association
- Primitive Baptist Universalists
- Generally capitalized "b. U." – Dowley 1977 Larsen 2011 Robertson 1929 BFER 1882 PTR 1929 New Encyclopædia Britannica 1987. See Wikipedia:Manual of Style (capital letters), article English capitalisation cites source: L. Sue Baugh, Essentials of English Grammar: A Practical Guide to the Mastery of English (9780844258218) Second Edition 1994 p59 "Religious Names and Terms: The names of all religions, denominations, and local groups are capitalized." Uncapitalized: Ankerberg.
- Tuggy, Dale, (2009). Stanford Encyclopedia of Philosophy[permanent dead link]. Accessed 10-30-2010
- Unitarianism Archived 2012-04-11 at the Wayback Machine The Columbia Electronic Encyclopedia (2007). Accessed 10-30-2010
- only once in Williams, The Polish Brethren : Documentation of the History and Thought of Unitarianism in the Polish-Lithuanian Commonwealth and in the Diaspora 1601–1685, Scholars Press, 1980, ISBN 0-89130-343-X
- The works of Sir John Suckling: Volume 1 ed. Thomas Clayton, Lester A. Beaurline – 1971 "'Socinianism' was both a flexible body of contemporary Biblical-Unitarian doctrine, formalized in 16th-century Italy chiefly by Faustus Socinus, and a catchword 'used to cover different kinds of unorthodox religious opinion."
- Stephen D. Snobelen, "Isaac Newton: His life and religion," in Arri Eisen and Gary Laderman, eds., Science, religion, and society: An encyclopedia of history, culture, and controversy, vol. 1 (Armonk, NY: ME Sharpe, 2007), "A manuscript list of twelve statements distinguishing God from Christ according to his biblical unitarian theology confirms this association and reveals that it has a heretical corollary. Newton asserts that it is only the Father who is [God]"
- Chapter 2. Mortimer Rowe, B.A., D.D. The History of Essex Hall. London: Lindsey Press, 1959. Full text reproduced here Archived 2012-01-16 at the Wayback Machine.}
- Gerald Parsons Religion in Victorian Britain Vol 3- 1988 p80 "Comprised of two theologically incompatible strands (one Bible-based, orthodox and distinguished from the rest of evangelical dissent only by its conviction that the doctrine of the Trinity was unscriptural; the other heir to the rationalism and deism of the Enlightenment and possessed of a calm and intellectual rather than fervent and ethos, Unitarianism was always destined to be firmly middle class."
- R. K. Webb "Miracles in English Unitarian Thought" Essay, chapter 6 in ed. Mark S. Micale, Robert L. Dietle, Peter Gay Enlightenment, passion, modernity: historical essays in European Thought and Culture 2007 p120 cf ref 22 p423 "Compare Richard Wright, the celebrated Unitarian missionary, An Essay on the Miraculous Conception of Jesus Christ (London, 1808)."
- Wright A review of the missionary life and labors of Richard Wright p68 "After they were excited to think freely, some gave up the doctrine of the miraculous conception, from reading the scriptures only, and observing certain things there with which it could not be reconciled."
- Robert Spears The Unitarian handbook of scriptural illustrations & expositions 1883 "The prophet uses not the Hebrew word which properly signifies a virgin, but which denotes a girl, a young woman. ... Originally and literally this seems applicable only to the birth of a child, a sign to Ahaz,"
- New Encyclopædia Britannica 1987 p264; same article also appears Merriam-Webster's encyclopedia of world religions – 1999, p1117
- James Oswald Dykes, James Stuart Candlish, Joseph Samuel Exell – 1882 "Waning of Biblical Unitarianism. Testament criticism, Dr. Ezra Abbot, of the Boston Unitarian School of Divinity, and, as a member of the American Revision Company is justly looked up to as an authority in that department, has published ..."
- Clayden Samuel Sharpe: Egyptologist and Translator of the Bible Page 247-248
- Tim Dowley Eerdman's handbook to the history of Christianity 1977 p496 "But in the 1830s James Martineau and some younger Unitarians led a revolt against biblical Unitarianism and its dogmas. They advocated a less argumentative religion. They wanted a more refined, romantic and devotional spirituality."
- Robertson J. M. History of Freethought in the Nineteenth Century Vol2 429:"Samuel Sharpe, the scholarly "Biblical Unitarian," though he had championed the cause of James Martineau (with whom he did not agree) when the party of Grote objected to making him Professor of Philosophy at University College, spent much of his time in his latter years in combating the new movement.
- The Princeton theological review: Volume 27 (1929) "Dr. Gow stresses the fact that the older Unitarianism was professedly a Biblical Unitarianism. Its advocates rejected such doctrines as the Trinity and the Atonement not so much on the ground that they were unreasonable as on the ground that they were [unscriptural]
- Henry Gow The Unitarians Methuen 1928
- Peaston A. E. The Prayer book reform movement in the XVIIIth century 1940 Until the year 1862, the theology championed by Lindsey and Priestley, and perfected by Lindsey's biographer Belsham, had been a Biblical Unitarianism, deriving its inspiration and authority from the Holy Scriptures
- Alexander Elliott Peaston The Prayer book reform movement in the XVIIIth century 1940 "The Book of Common Prayer as revised by Lindsey immediately attracted those Presbyterians who had been anxious for a liturgy, and whose theology, under the influence of Priestley was becoming Biblical Unitarian."
- Worship and theology in England: Volume 4 1970 "These four forms of corporate worship have several common characteristics and together may be regarded as typical of Biblical Unitarianism. The belief in miracles and supremely in the miracle of the Resurrection of Jesus is dominant"
- Recusant history: Volume 25, Issues 1–2 Catholic Record Society (Great Britain) – 2000 "Geddes, indeed, dealt a potentially serious blow at the biblical Unitarianism of Joseph Priestley by his contributions to the mythological interpretation of the scriptures themselves, and by his association with the German school of biblical criticism.
- Walter H. Burgess Transactions of the Unitarian Historical Society: Volumes 8–9 "The struggle between Biblical Unitarianism and the newer Unitarianism is seen in the controversy between Dr. Charles Lloyd, Principal of Carmarthen, and Gwilym Marles on "Saving Faith."
- D. Elwyn Davies "They thought for themselves": a brief look at the story of Unitarianism in Wales 1982 "And it was a disagreement regarding the above philosophical principle that caused yet another major controversy between Gwilym Marles and his old Principal Tutor at Carmarthen, Dr. David Lloyd, regarding the meaning of Saving Faith."
- Stange, Charles Douglas British Unitarians against American slavery, 1833–65 – Page 54: "[George] Harris was one of the originators of the Scottish Unitarian Association in 1813, and a supporter of "old biblical Unitarianism."
- A History of Unitarianism: Socinianism and Its Antecedents etc., Harvard University Press, 1945.
- Lawrence Pearsall Jacks, George Dawes Hicks, George Stephens Spinks The Hibbert journal: Volumes 49–50 1950 "But it may be of service to the reader interested in the fourth section to be reminded of the fine collections of semi-Arian and Biblical Unitarian liturgies in the libraries of Manchester College, Oxford, and the Unitarian College,"...
- The London quarterly & Holborn review: Volume 169 1944 [Robert Rodolph] Suffield was at Croydon from 1871 until 1877. It was a period of theological strain among English Unitarians. The heirs of the older Presbyterianism clung to a Biblical theology with a strongly Christocentric outlook. It was for this reason that Suffield refused to call his church by the Unitarian name, a label associated popularly with William Gaskell, Robert Spears, and the narrowly Biblical type of liberal theologian. He chose the designation of 'Free Christian Church', the title which brought him nearest to Parker and the New England Transcendentalists..... Faith finds its authority either in the intellectual and moral acceptance of some outward revelation, a church or a book, or in the alternative of an attitude of reliance upon the dictates of the individual conscience. To Suffield, the two positions were sharply divided; the older Biblical Unitarian "
- Timothy Larsen A People of One Book: The Bible and the Victorians 2011 p143 "In 1876 (over fifteen years after Parker's death and the year before Carpenter's own death), the English biblical Unitarian Robert Spears resigned his post with the British and Foreign Unitarian Association because of a plan to republish Parker's works.
- Douglas C. Stange British Unitarians Against American Slavery, 1833-65- 1984 p. 54 "Harris was one of the originators of the Scottish Unitarian Association in 1813, and a supporter of "old biblical Unitarianism." "
- Christopher Hill, Milton and the English Revolution, p. 290.
- Polish Socinians: FROM THE POLISH SOCINIANS TO THE AMERICAN CONSTITUTION, Marian Hillar, A Journal from the Radical Reformation, A Testimony to Biblical Unitarianism, Vol. 4, No. 3, pp. 22–57, 1994
- e.g. David Kemball-Cook Is God a Trinity? Page 64 "Graeser, Lynn and Schoenheit, in One God and One Lord represent the biblical unitarian view that Jesus was an anointed man. They argue against the Trinity on both logical and biblical grounds, and they reject the 'God-man' idea...""
- P. R. Lackey The Tyranny of the Trinity: The Orthodox Cover-up 2008 Page 347 "Her strong conviction led her to collaborate with biblical unitarian authors to create a book that challenges the centuries-old man-made doctrine of the Trinity, the mainstay of ecclesiastical tradition. "
- J. D. Bowers Joseph Priestley and English Unitarianism in America – concluding chapter: 'The Death and Resurrection of English Unitarianism' – p. 251: "There are others who even hope to bring back Priestley's theology. They see Socinianism as a potentially important and shaping force in the (re)creation of a new Unitarian theology, one that returns to the old principles and teachings. Anthony Buzzard has been a leading Unitarian proponent in arguing for a return to Christian traditions. Joined by other theologians, including Charles F. Hunting, Buzzard has written numerous "evangelical" works (from a Unitarian standpoint), that argue for a return to a belief in Jesus as the Messiah". This model is a return to the beliefs expressed by Priestley, when he argued for the restoration of biblical faith, hoped for an increased fellowship with Christians, and at the same time, argued from scripture against the doctrine of the Trinity."
- Eyre, Alan Brethren in Christ CSSS Adelaide.
- General Assembly of Unitarian and Free Christian Churches, UK
- Wilson, Andrew R. The History of the Christadelphians 1864–1885 : The Emergence of a Denomination Shalom, 1997
- Thomas, John. 1870. Phanerosis: an Exposition of the Doctrine of the Old and New Testament, Concerning the Manifestation of the Invisible Eternal God in Human Nature, Etc. Birmingham, p. 84 (online)
- R. J. Hyndman, "Biblical Monotheism Today". In T. Gaston (ed.), One God, the Father (2013).