For that purpose it will be necessary to give a brief sketch of the early heresies in so far as they bear on the Christological problem. The two primitive forms of doctrinal error, to which the Church, even in apostolic days, was exposed, were docetism and ebionitism. These are the elemental heresies. All the later Christological heresies are refinements of one or other of these two.
Its Christian antecedents comprised positive and negative currents. The positive current was docetism, the negative ebionitism. Docetism, originating in apostolic times, passed through many phases, to provide, at the end of the fourth century, in its most refined form, Apollinarianism, the immediate positive cause of monophysitism.
They constitute the extremes of Christological thought: between them runs the via media of orthodoxy. Each of the two sees but one aspect of the two-fold life of Christ. Docetism lays an exclusive emphasis on His real divinity, ebionitism on His real humanity. Each mistakes a half truth for a whole truth. The docetists denied that Jesus Christ had come in the flesh.
And will not this presumption be transformed into certainty if we recognize in the doctrine universally rejected by the Church the characteristic features of one of the religions of the past? To say that gnosticism or ebionitism are legitimate forms of Christian thought, one must boldly deny the existence of Christian thought at all, or any specific character by which it could be recognized.
Ebionitism, related to docetism as realism to idealism, possessed equal vitality and equal adaptability. It showed itself in various humanistic interpretations of Christ. Of these the most elaborate was Nestorianism, which exerted the most insistent and immediate negative influence on the early growth of monophysitism.
In conflict with the heresies which arose in the next two generations, she evolved a positive statement of the truth. Opposition to Apollinarianism gave rise to the Nestorian heresy. The original ebionitism had died away, but its spirit and central doctrine reappeared in Nestorianism. Nestorianism might be described as ebionitism conforming to the creeds of Nicaea and Constantinople.
The rigid monotheism of the Jews made it hard for them to conceive an intermediary between God and man; they were naturally disposed to embrace a humanistic explanation of Christ. Docetism was elaborated by Valentinus, Manes and other gnostics and adopted into their systems, while ebionitism provided the basis for the Christologies of Paul of Samosata, of the Photinians and Adoptionists.
They did not revert to crude ebionitism, but they explained the Nicene creed from an ebionitic stand-point. They maintained as against the Apollinarians the completeness of Christ's human nature; with equal vigour they maintained the essential deity of the Logos. The union, according to the Nestorians, was subsequent to the conception of Jesus. It was not a personal, but a moral union.