TRINITY, DOCTRINE OF TUE. A doctrine of theology which declares that there are three per sons in the Godhead, or divine nature—the Father, the Son, and the Holy Ghost—and that "these three are one true eternal God, the same in substance, equal in power and glory—although distinguished by their personal properties." The most elaborate statement of the doctrine is to be found in the Athanasian Creed, which asserts that "the Catholic faith is this: That we worship one God in Trinity, and Trinity in Unity— neither confounding the persons nor dividing the substance—for there is one person of the Father, another of the Son, and another of the Holy Ghost. But the Godhead of the Father, and of the Son, and of the Holy Ghost is all one; the glory equal; the majesty co-eternal." The doctrine is not found in its fully developed form in the Scriptures; but it is supposed to be clearly revealed in its elements in the New Tes tament, and also to be indicated in many of the statements and revelations of the Old Testament. The form of expression in speaking of God in the Old Testament Scriptures—the plural El-o him, coupled with a singular verb; the apparent distinction recognized in the revelations to the patriarchs and Moses between Jehovah and 'the angel of Jehovah ;' the mode in which 'the Spirit' and 'word' of God, and 'wisdom' (Prov erbs viii.) are spoken of ; and the gradual unfold ing of the doctrine of a 'Messiah,' have all been taken as indications from the earliest times of the truth of a plurality of persons in the God head; and in the New Testament Scriptures the doctrine is represented as clearly taught in the Trinitarian formula of baptism—the general character of the claims and prerogatives of Jesus Christ by which His true deity is established, and in the functions attributed to the Holy Spirit. The evidence is held conclusive of the equal divine nature and yet distinct personality of the Son and the Spirit along with God the Father. It is generally conceded, however, that the Christians of the second and even of the third century did not treat the subject with the same definiteness and accuracy of expression as later writers. They were content for the most
part to use Scriptural expressions iu speaking of the Father, and the Son, and the Spirit, without defining articulately their relation to one an other. It was not until the progress of opposing parties sought, on the one hand, to degrade the divine dignity of Christ (Ebionitism in its vari ous forms, and Arianism) , or, on the other hand, to confound the personality of Christ with God the Father (see MONARCIIIANS), that the Church was led to define in the Nicene Creed the relation of the Son to the Father, and further, in the Nictrno-Constantinopolitan Creed, the relation of the Spirit to the Father. This creed (see NICENE CREED: FILIOQUE) was specially directed against the opinions of Arius (q.v.).
The evidence, here briefly sketched in outline, has been accepted as satisfactory, not only by the Roman Catholic and Oriental communions. but also by all the great Protestant communions. The only exception in modern times to the reception of the doctrine is in the case of the Socinians or Unitarians (see Loci:yrs). who occupy in their teaching very much the position of the ancient Humanitarians ( Ebionites). Consult the vari ous treatises on systematic theology; Bauer, Die christliehe Echo. von dcr Dreieinigkeit (3 vols., Tiibingen, 1841-43) ; Meier, Die LOOT von der Trinitdt (Hamburg, 1844) ; Darner, 7Vic His tory of the Development of the Doctrine of the Person of Christ (Eng. trans., Edinburgh, ; id., History of Protestant Theology (ib., 1871) ; Burris, The Trinity (Chicago, 1874) ; Steenstra, The Being of God us Unity and Trin ity (Boston, 1891) ; on the antitrinitarian side, Norton, A 8tatement of /bosons for Not Believ ing the Doctrines of Trinitarians (2d ed., Boston, 1S56) ; Clarke, Orthodoxy, Its Truths and Errors (ib., 1866).