John Quincy Adams to Abigail Adams, 5 December 1815 (Excerpts):
“That the Athanasian Trinity is clearly contained in the Scriptures, I have not been able to convince my own mind beyond a question; but if I must choose between that and the belief that Christ was a mere man, to be compared with Socrates, and must mutilate the New Testament to suit the critical scruples of Dr Priestley in order to maintain this creed, I have no hesitation in making my choice. I find in the New Testament Jesus Christ accosted in his own presence by one of His disciples as God without disclaiming the appellation. I see him explicitly declared by at least two other of the Apostles to be God, expressly and repeatedly announced, not only as having existed before the worlds, but as the Creator of the worlds without beginning of days or end of years. I see him named in the great prophecy of Isaiah concerning him the mighty God! and I cannot be entirely satisfied to be told that one of the expressions is merely a figure, that another may be an interpolation, and a third is not perhaps correctly translated; nor yet, as I am told by Mr. Channing, that solitary texts collected here and there may be found in the Bible to support any doctrine whatsoever. The texts are too numerous, they are from parts of the Scriptures too diversified, they are sometimes connected by too strong a chain of argument, and the infer ences from them are to my mind too direct and irresistible, to admit of the explanations which the Unitarians sometimes attempt to give them, or of the evasions by which at others they endeavor to escape from them. It is true the Scriptures do not use the term persons where they countenance the doctrine of the Trinity, and perhaps it may be difficult, perhaps impossible, to give a definition of the term person which shall solve the mystery, or save to human reason the apparent inconsistency of an identity in three and one. But can the Unitarian give a more intelligible definition of the term one as applied to the Deity? Is his God infinite? Is he omnipresent? Is he eternal? And if so what precise idea can he form of unity, without bounds or dimensions? For my part the term one necessarily implies to me the limits or bounds within which that one is included, and beyond which it is not. How then can number be applicable to the idea of God any more than time or space? It is therefore as difficult for me to conceive that God should be one, as that he should be three, or three in one. How it can be, I know not; but in either hypothesis the idea of God is to me equally incomprehensible. The question, therefore, is not whether the doctrines of the Trinity be incomprehensible, but whether it be contained in the Scriptures. You say that you are an Unitarian according to the creed of Dr. Clarke, and Mr. Channing intimates the same of himself, and of our liberal Christians in general; now, although I have read the Bible I have not read Dr. Clarke, and therefore will take the sub stance of his creed as stated by Mr. Channing. He says that “Doctor Clarke believed that the Father alone is the Supreme God, and that Jesus Christ is not the supreme God, but derived his being and all power and honor from the Father, even from an act of the Father’s power and will. He maintains that as the Scriptures have not taught us the manner in which the son derived his existence from the Father, it is presumptuous to affirm that the son was created, or that there was a time when he did not exist. ” Now this creed contains as complete an inconsistency as trinity in unity. How could Jesus Christ derive his being from the Father without being created? And if he existed before all time, how could he derive his being at all ? According to this creed Jesus Christ might exist before he had his being, and Dr. Clarke escapes from the Trinity, only to plunge himself into a contradiction in terms equally unintelligible.
I trust that neither you nor my father will think that I am presuming to offer you anything new in support of Athanasianism. My own opinions on this subject have re sulted solely from the impression of the Scriptures upon my own mind; the very little of controversy that I have read relating to it has rather tended to confirm than weaken that impression. In the management of this controversy I have not had occasion to admire the Christian temper of the opponents on either side… You will see in the memoirs of the life of Dr. Price that that worthy man was offended with the affectation with which Dr. Priestley and his sectaries arrogated to themselves exclusively the appellation of Unitarians. There is certainly something disingenuous in it, inasmuch as it implies that the Trinitarians are not Unitarians, and insinuates that they believe in a plurality of gods. There is something of a similar spirit in the epithet of liberal clergymen which our anti-Trinitarians appear disposed to appropriate to themselves. The same misuse of the term orthodoxy must perhaps be charged upon their antagonists.”
Source: John Quincy Adams, The Writings of John Quincy Adams, edited by Worthington Chauncey Ford (New York: The MacMillan Company, 1915) Vol. V, pp.432-435, letter to Abigail Adams, 5 December 1815.