If there were some who sacrificed the deity to the humanity of Christ, there were others who reversed the order. The Gnostics were profoundly influenced by the dualistic conception of the Greeks, in which matter, as inherently evil, is represented as utterly opposed to spirit, and by a mystic tendency to regard earthly things as allegorical representations of great cosmic redeeming processes. They rejected the idea of an incarnation, a manifestation of God in a visible form, since it involved a direct contact of spirit with matter. Harnack says that the majority of them regarded Christ as a Spirit consubstantial with the Father. According to some, He descended upon the man Jesus at the time of His baptism but left Him again before His crucifixion while, according to others, He assumed a merely phantasmal body.
The modalistic Monarchians also denied the humanity of Christ, partly in the interest of His deity and partly to preserve the unity of the divine Being. They saw, in Him, merely a mode or manifestation of the one God, in whom they recognized no distinction of persons. The anti-Gnostic and Alexandrian fathers took up the defense of the deity of Christ but, in their defense, did not altogether escape the error of representing Him as subordinate to the Father. Even Tertullian taught a species of subordination, but especially Origen, who did not hesitate to speak of a subordination as to essence. This became a stepping-stone to Arianism, in which Christ is distinguished from the Logos as the divine reason and is represented as a pre-temporal superhuman creature, the first of the creatures, not God and, yet, more than man. Athanasius took issue with Arius and strongly defended the position that the Son is consubstantial with, and of the same essence as, the Father, a position that was officially adopted by the Council of Nicea in 321. Semi-Arianism proposed a via media by declaring the Son to be of a similar essence as the Father.
From: Systematic Theology by Louis Berkhof (Grand Rapids: William B. Eerdmans Publishing Company, 1939), p. 306.