The third question, How are we to conceive of the union of Deity and humanity in Him? is a problem which exercised the Fourth, Fifth and Sixth Centuries of the Christian Church to the exclusion of almost all others. The theologians of those times worked out (and fought out) the theory of the union of two “natures” in one “Person,” which remains the official statement of the Church’s interpretation of Christ in Greek, Roman and Protestant creeds. But the philosophy which dealt in “natures” and “persons” is no longer the mode of thought of educated people; and while we may admire the mental skill of these earlier theologians, and may recognize that an Athanasius and his orthodox allies were contending for a vital element in Christian experience, their formulations do not satisfy our minds.
In the last century some divines advanced a modification of this ancient theory, naming it the Kenotic or Self-emptying Theory, from the Greek word used by St. Paul in the phrase, “He emptied Himself.” The eternal Son of God is represented as laying aside whatever attributes of Deity—omnipresence, omniscience, omnipotence, etc.—could not be manifested in an entirely human life. The Jesus of history reveals so much of God as man can contain, but is Himself more. But we know of no personality which can lay aside memory, knowledge, etc. The theory begins with a conception of Deity apart from Jesus, and then proceeds to treat Him as partially disclosing this Deity in His human life; but the Christian has his experience of the Divine through Jesus, and his reflection must start with Deity as revealed in Him.
Still later in the century, Albrecht Ritschl gave another interpretation of Christ’s Person. He began with the completely human Figure of history, and pointed out that it is through Him we experience communion with God, so that to His followers Jesus is divine; His humanity is the medium through which God reveals Himself to us. This affirmation of His Deity is an estimate, made by believers, of Jesus’ worth to them; they cannot prove it to any who are without a sense of Christ’s value as their Saviour. Any further explanation of how the human and the Divine are joined in Jesus, he deemed beyond the sphere of religious knowledge.