Joseph Priestley (1733-1804)
Unitarianism was one of the most popular religious errors among eighteenth-century Dissenters in England. Along with Universalism, which was also all the rage in some circles, Unitarianism challenged the longstanding evangelical consensus among Dissenters and led to a long-term spiritual declension among English Congregationalists and Presbyterians in particular. Though he wasn’t the first Unitarian in England, the famous philosopher, chemist, and political theorist Joseph Priestley was the key leader in the movement. American Unitarians such as Benjamin Franklin and Thomas Jefferson were influenced by Priestley’s writings on the topic.
In 1793, Andrew Fuller wrote one of the key refutations of Unitarianism, challenging the sentiments of Priestley and others Unitarian luminaries such as Theophilus Lindsey. The latter founded the first Unitarian congregation in England in 1774. Fuller titled his broadside The Calvinistic and Socinian Systems Examined and Compared, As To Their Moral Tendency, In A Series of Letters, Addressed to the Friends of Vital and Practical Religion. Much to the chagrin of the Unitarians, Fuller equated their movement with Socinianism, a similar heresy that began among some Radical Reformers in Poland in the late sixteenth century. Socinians and English Unitarians denied the full inspiration of Scriptures, the necessity of atonement for salvation, and, of course, the full deity of Christ.
Fuller closes The Calvinistic and Socinian Systems Examined and Compared with a couple of paragraphs that summarize the differences between orthodox Trinitarianism and the Unitarians. I believe these same arguments could be raised against any heretical system of belief that attempts to improve upon Christianity, but in fact represents a departure from the apostolic gospel.
First, If that system which embraces the Deity and atonement of Christ, with other correspondent doctrines, be friendly to a life of sobriety, righteousness, and godliness; it must be of God, and it becomes us to abide by it; not because it is the doctrine of Calvin, or of any other man that was uninspired, but as being “the gospel which we have received” from Christ and his apostles; “wherein we stand, and by which we are saved.”
Secondly, If that system of religion which rejects the Deity and atonement of Christ, with other correspondent doctrines, be unfriendly to the conversion of sinners to a life of holiness, and of professed unbelievers to faith in Christ; if it be a system which irreligious men are the first and serious Christians the last to embrace; if it be found to relax the obligations to virtuous affection and behaviour, by relaxing the great standard of virtue itself; if it promote neither love to God under his true character, nor benevolence to men, as it is exemplified in the spirit of Christ and of his apostles; if it lead those who embrace it to be wise in their own eyes, and instead of humbly deprecating God’s righteous displeasure, even in their dying moments, arrogantly to challenge his justice; if the charity which it inculcates be founded in an indifference to divine truth; if it be inconsistent with ardent love to Christ, and veneration for the Holy Scriptures; if the happiness which it promotes be at variance with the joys of the gospel; and, finally, if it diminish the motives to gratitude, obedience, and heavenly-mindedness, and have a natural tendency to infidelity; it must be an immoral system, and consequently not of God. It is not the gospel of Christ, but “another gospel.” Those who preach it preach another Jesus, whom the apostles did not preach; and those who receive it, receive another spirit, which they never imbibed. It is not the light which cometh from above, but a cloud of darkness that hath arisen from beneath, tending to eclipse it. It is not the highway of truth, which is a way of holiness; but a by-path of error, which misleads the unwary traveller, and of which, as we value our immortal interests, it becomes us to beware. We need not be afraid of evidence, or of free inquiry; for if irreligious men be the first, and serious Christians be the last, who embrace the Socinian system, it is easy to perceive that the avenues which lead to it are not, as its abettors would persuade you to think, an openness to conviction, or a free and impartial inquiry after truth, but a heart secretly disaffected to the true character and government of God, and dissatisfied with the gospel way of salvation.
See Andrew Fuller, “The Calvinistic and Socinian Systems Examined and Compared, As To Their Moral Tendency, In A Series of Letters, Addressed to the Friends of Vital and Practical Religion,” in The Complete Works of the Rev. Andrew Fuller, edited by Joseph Belcher (Philadelphia: American Baptist Publication Society, 1845; reprint, Harrisonburg, VA: Sprinkle, 1988), p. 233. Emphasis in original.