The union of three in one; generally applied to the ineffable mystery of three persons in one God,– Father, Son, and Holy Spirit. This doctrine is rejected by many because it is incomprehensible; but, as Mr. Scott observes, if distinct personality, agency, and divine perfections, be in Scripture ascribed to the Father, and to the Son, and to the Holy Spirit, no words can more exactly express the doctrine, which must unavoidably be thence inferred, than those commonly used on this subject, viz. that there are three distinct Persons in the Unity of the Godhead. The sacred oracles most assuredly teach us, that the One living and true God is, in some inexplicable manner, Triune, for he is spoken of, as One in some respects, and as Three in others, Gen 1:26, Gen 2:6,7. Is 48:16. Is 34:16. 2 Cor 13:14. Jn 14:23. Matt 28:19. 2 Thess 3:3. 1 Jn 5:7. Acts 5:3,4. The Trinity of Persons in the Diety consists with the Unity of the Divine Essence; though we pretend not to explain the modus of it, and deem those reprehensible who have attempted it; as the modus in which any being subsists, according to its distinct nature and known properties, is a secret to the most learned naturalists to this present day, and probably will always continue so. But if the most common of God’s works, with which we are the most conversant, be in this respect incomprehensible, how can men think that the modus existetendi (or manner of existence) of the infinite Creator can be level to their capacities?—The doctrine of the Trinity is indeed a mystery, but no man hath yet shown that it involves in it a real contradiction. Many have ventured to say, that it ought to be ranked with transubstantiation, as equally absurd. But Archbishop Tillotson has shown, by the most convincing arguments imaginable, that transubstantiation includes, the most palpable contradictions; and that we have the evidence of our eyes, feeling, and taste, that what we receive in the Lord’s supper is bread, and not the body of a man; whereas we have the testimony of our eyes alone, that the words “This is my body,” are at all in the Scriptures. Now this in intelligible to the meanest capacity: it is fairly made out, and perfectly unanswerable: but who ever attempted thus to prove the doctrine of the Trinity to be self-contradictory? What testimony of our senses, or what demonstrated truth, does it contradict? Yet till this be shown, it is neither fair nor convincing, to exclaim against it as contradictory, absurd, and irrational.”
Charles Buck (1771-1815) was an English Independent minister, best known for the publication of his “Theological Dictionary”. According to the “Dictionary of National Biography”, a Particular Baptist minister named John C. Ryland (1723-1792) assisted Buck by writing many of the articles for the aforementioned publication. One may conclude, based not only Buck’s admiration for his friend Ryland, but also on the entries in his Theological Dictionary, that he stood head and shoulders with the High-Calvinists of his day.