We finally arrive at the burning question of Christology. As much as we may be appreciative of some of the things Harnack has said (particularly his critique of asceticism and Tolstoy's anarchism), as much as we may acknowledge the depth of his sense of filial relationship with God as Father, at the end of the day, Harnack is without question outside the bounds of historic orthodoxy when it comes to Christology.
He begins with a general disdain for what he calls "the gruesome story" of the church's debates over Christology (p. 125). The very concept of "heresy" was forged in the fires of the Christological and Trinitarian debates of the first four centuries of the church and its battles with Docetism, Arianism, Nestorianism, Monophysitism, and other views.
In the course of this controversy men put an end to brotherly fellowship for the sake of a nuance; and thousands were cast out, condemned, loaded with chains and done to death. It is a gruesome story. On the question of "Christology" men beat their religious doctrines into terrible weapons, and spread fear and intimidation everywhere. (p. 125)
You can almost sense the anger in Harnack's voice. He views these Christological fine points as so much theological hair-splitting, the equivalent of debating how many angels can fit on the point of a needle. Worse still, Christians condemned, excluded, and even killed one another over such differences.
After these highly prejudicial remarks, Harnack proceeds to lay down two leading points as the basis for his Christology:
First, Jesus only demanded obedience to his commandments, not exalted metaphysical speculations about his deity:
He desired no other belief in his person and no other attachment to it than is contained in the keeping of his commandments. (p. 125) ... His message is simpler than the churches would like to think it. (p. 143)
Second, Jesus regarded God as his Father in such a submissive manner that it precludes any notion of Jesus being equal with God:
He described the Lord of heaven and earth as his God and his Father; as the Greater, and as Him who is alone good. He is certain that everything which he has and everything which he is to accomplish comes from his Father. He prays to Him; he subjects himself to His will; he struggles hard to find out what it is and to fulfill it. (p. 126)
The point is, Jesus could not have regarded himself as in some sense divine or equal with God, if he was in complete submission to God.
Taking his cue from these two starting points, Harnack then attempts to explain the meaning of the two Christological titles, "Son of God" and "Messiah."
"Son of God"
Harnack appeals to Matt 11:27: "All things have been handed over ot me by my Father, and no one knows the Son except the Father, and no one knows the Father except the Son and anyone to whom the Son chooses to reveal him" (ESV). This seems to suggest that the sonship of Jesus in relation to the Father has something to do with the knowledge of God.
The name of Son means nothing but the knowledge of God ... Jesus is convinced that he knows God in a way in which no one ever knew Him before, and he knows that it is his vocation to communicate this knowledge of God to others by word and by deed--and with it the knowledge that men are God's children. (p. 128)
In other words, Jesus' relationship to the Father, his sonship, is not absolutely unique and ontologically distinct from our relationship as children of God. It is different in degree only--no one knew God and related to him as Father with the same perfection and intensity that Jesus did. His vocation is to bring others into the same relationship that he enjoyed.
"Messiah"
The concept of "Messiah" was rooted in a long history of Israel's promises, prophecies, and hopes. It was also tied to Israel's national hopes in which the God-sent Messiah would destroy Israel's enemies and be established as the ruler of the nations.
But for Jesus, these ideas were but husk to be discarded. For Jesus, his Messianic consciousness had to do with his dawning awareness, culminating in his baptism, when he realized that his vocation was to lead men to God.
He is the way to the Father, and as he is the appointed of the Father, so he is the judge as well. Was he mistaken? Neither his immediate posterity, nor the course of subsequent history, has decided against him. It is not as a mere factor that he is connected with the Gospel; he was its personal realization and its strength, and this he is felt to be still. Fire is kindled only by fire; personal life only by personal forces. Let us rid ourselves of all dogmatic sophistry, and leave others to pass verdicts of exclusion. (p. 145)
Does Harnack affirm the deity of Christ? Clearly not in any orthodox sense. But he does affirm the deity of Christ in a highly attenuated form. For Harnack, Jesus is "divine" only in the sense that this is what he means to us:
No one who accepts the Gospel, and tries to understand him who gave it to us, can fail to affirm that here the divine appeared in as pure a form as it can appear on earth. (p. 146)
To say that Jesus is divine is therefore merely a value judgment (Kant), an expression of the significance that the man Jesus has for us as the living fire that kindles the same religious fires in us, for as we get to know Jesus we are brought closer to the Father whom he proclaimed.
Perhaps the best way to summarize Harnack's Christology is by quoting the following slogan:
The Gospel, as Jesus proclaimed it, has to do with the Father only and not with the Son. (p. 144)
This was the statement at which orthodox Christians in Harnack's day took greatest offense, and rightly so. It is not only offensive; it is contrary to the Gospels themselves, which everywhere present Jesus as calling people to personal faith in his own person. Contrary to Harnack's unitarianism, the Gospel, as Jesus proclaimed it, certainly does have to do with the Son.