Classical Unitarianism has a rich and complex history during which major theologians produced some outstanding and influential writings.   

Unfortunately, the most important texts in the development of Unitarianism are rarely found these days in proper book or e-book formats.  Some books are sold as reprints but these are often poorly laid out and expensive.  However, many Classical Unitarian texts are available to view, for free, in online archives.  These are, for the most part, easily readable, free, and it is often possible to download PDFs which can be read on Kindles.

The following list of links will allow you to read some of the most significant classical Unitarian texts but it is far from comprehensive. Many other works are available online and you are encouraged to search for them. N.B. Some of these texts are a lot easier to read than others.

Across Britain a movement of ‘rational dissenters’ gradually adopted the name Unitarianism in the eighteenth century. Although the name was new, the core of their distinctive theology had actually been worked out in the sixteenth and seventeenth century as radical underground reformers risked everything to question some of the key doctrines of Christianity. 

Michael Servetus (1509/11-1553)

Leading the way was the brilliant, speculative and brave (some might say foolhardy) theology of Michael Servetus.  In the heat of the Reformation he argued against the Trinity and other key doctrines that had either been retained or developed by the Reformers. This led to his trial and gruesome martrydom. 

Two Treatises of Servetus on the Trinity

But while Servetus was given a place of honour, what came to be known as Unitarianism really took cohesive shape with the writings and leadership of Faustus Socinus and, in the early days, Unitarians were known as Socinians.  

Faustus Socinus (1539-1604) and Socinianism

The Racovian Catechism

This text was produced by the Polish Brethren, the Socinian movement centred on Raków. It was published after the death of Socinus. It represents, therefore, the beliefs of the faith community among whom Socinus had recently lived, and which looked to him for theological leadership.

There are many exisiting works by Socinus himself, and many others from the Polish Bretheren, but these have yet to be translated from Latin. 

Biography: The life of that incomparable man, Faustus Socinus Senensis, described by a Polonian knight.: Whereunto is added an excellent discourse, which the same author would have had premised to the works of Socinus; together with a catalogue of those works.

The name Unitarianism was applied to those rational dissenters who, in the eighteenth century, were influenced by the distinctive theology of Socinus and John Biddle . 

John Biddle (1615-1662)

John Biddle  is known as the Father of English Unitarianism. He did not read Socinian works until after he had independently developed a strikingly similar theology, albeit with some fascinating differences from Socinus. 

John Biddle’s Twofold Catechism

The apostolical and true opinion concerning the Holy Trinity, revived and asserted; twelve arguments levyed against the traditional and false opinion about the Godhead of the Holy Spirit

A review of the life, character and writings of the Rev. John Biddle, … By Joshua Toulmin, …  1791

Joseph Priestley (1733-1804)

A leading intellectual of his day, was in the vanguard of the emerging Unitarian movement in England and America in the eighteenth century. His theology clearly builds on Socinus and Biddle but differs in important respects, from them and from other emerging Unitarian thinkers.  By the time of Priestley we see the fruits of the Enlightenment combining with Socinian theology to create a form of Christian Unitarianism that is still recognisable today.   

Institutes of Natural and Revealed Religion, Volume One

Institutes of Natural and Revealed Religion, Volume Two

A History of the Corruptions of Christianity

Theophilus Lindsey (1723-1808)

A friend of Priestley, Lindsey was an Anglican vicar who resigned his position on adopting Unitarian beliefs. He opened the first explicitly Unitarian church in London in 1774. 

The apology of Theophilus Lindsey, M.A. on resigning the vicarage of Catterick, Yorkshire. 1774

Thomas Belsham (1750-1829)

Assumed leadership after the death of Lindsay, responsible for supporting the growth of Unitarianism into a nationally recognised tradition.

The importance of truth, and the duty of making an open profession of it 

William Ellery Channing (1780-1842)

The pre-eminent figure as American Unitarianism emerged from the liberal wing of East Coast Congregaitonalism. Still a towering figure in the history of Unitarianism.

Works of William Ellery Channing

George Harris (1794 – 1859) 

As a child he was a friend of Thomas Belsham. Became a well known minister and tutor of ministers, so forming a link between the first days of Unitarianism and ministers such as Henry Green of Brook Street Chapel. 

Christian Unitarianism vindicated from the misrepresentations of J. C. Colquhoun and the Church of Scotland Magazine. Fifth edition

Sermons by George Harris

Andrews Norton (1786-1853)

Known as ‘The  Unitarian Pope’ because of his dominant position at Harvard Divinity School. He began his career fiercely contesting the Calvinism of previous generations. Towards the end he was a strong opponent of the drift away from Christianity towards Transcendentalism that affected some Unitarians.

Evidences of the Genuineness of the Gospels

Tracts Concerning Christianity

Discourse on the Latest Form of Infidelity

John Relly Beard (1800-1876)

A major figure in British Unitarianism as a minister, writer and educator. Involved in the founding of Unitarian College, Manchester. 

Reasons why I am a Unitarian: in a series of letters to a friend

The Autobiography of Satan

The religion of Jesus Christ defended from the assaults of Owenism : in nine lectures

Sermons

James Martineau (1805-1900)

Hugely dominant figure in his time. Led a revolt against the Christian Unitarianism of previous generations, tried unsuccessfully to have the movement renamed as Free Christian. He developed  distinctive beliefs of Free Christianity, but was also highly ecumenical, leading the movement against having any sort of creed.

His Free Christian theology is very different from Christian Unitarianism.

The Seat of Authority in Religion

Various other works by James Martineau

Robert Spears (1825 -1899)

A friendly rival of Martineau’s. More theologically conservative: as a minister, editor, denominational officer and author he was a strong voice for maintaining the Christian Unitarian (Unitarian Christian) theology.

The Unitarian Handbook of Scriptural Illustrations and Expositions

Arthur Long (1920-2006)

A very significant figure in twentieth century Unitarianism. As much of Unitarianism moved beyond, away from, and even against Christianity, he continued to preach a tolerant but distinct form of Christian Unitarianism.

“With the death of the Rev Dr Arthur Long on Saturday, 9 December [2006] our household of faith has lost its leading theologian and educator of recent times”

From more from this tribute.

Faith and Understanding: Critical Essays in Christian Doctrine