Labeling (and, its near cousin, generalization) has its own merits and demerits. By doing it we can characterize certain groups with their own distinctives. Of course, we are aware that one size does not fit all. But certainly a few sizes will fit almost of all (e.g., in a normal curve, mean ± twice of standard deviation will account for 95% of the data), although in the end there will still be outliers which won’t fit any single group. We also need to remind ourselves that even members in the same group are not totally uniform either.
Labeling could be useful as well for identity formation, especially if we wanted to define ourselves against others. For example, it is still common to find how we group the church into the orthodox and the liberals. And, not too seldom as well that liberals simply mean “those whom we disagree with.” This is a gross oversimplification (pun intended), of course, but the point still remains. If we define honestly and clearly what these labels constitute, they are still helpful in explaining different groups in the spectrum.
How does one group different types of Christology, then? It is interesting to read how Barth kept using two types as his sparring partners: docetic and ebionite Christology. In the end, it might be proved the best way to do it (or, on the other hand, it might be shown that Barth lumped unfairly options which should not be characterized as either docetic or ebionite), but I guess this simple classification fits with the way we believe who Jesus is: “very God and very Man.” (I/2, 25) I guess, for Barth, Docetism and Ebionitism represent the two poles of which we would fall into if we can’t hold these paradoxical theses together (and that it would be similar with Sabellianism and Tritheism in the case for the doctrine of the Trinity). I would close with an interesting analysis of Barth (is he true?) regarding the difference between the Christologies of Luther and Calvin:
“We are dealing with testimonies to one reality, which, though contrary to one another [i.e., very God and very Man], do not dispute or negate each other. That must be remembered when we are compelled to adopt a position towards the antitheses which repeat the same variety in Church history, namely between the Christologies of Alexandria and of Antioch, of Luther and of Calvin. It is in the succession of the Johannine type that we have obviously to see Eutyches’ and later Luther’s interpretation of Christ, [and] in the succession of the Synoptic type that of Nestorius and of Calvin.” (I/2, 24)