I'm curious why even the most "philosophical" of Christian theologians (e.g. Teilhard de Chardin, Barth) include Jesus in their theology. — Ciceronianus
In my mind, one reason is the importance of tradition within Christianity. If to be a Christian means to have faith in the basic tenets of Christianity, I think it's often overlooked that one huge cornerstone holding up this faith is the tradition of Christianity itself. The crumbling of this cornerstone for myself was one of the main reasons for losing my own former faith.
There's a two-thousand-year-old theological tradition that has it's roots in the rather forceful emergence of a catholic, orthodox faith in the face of both persecution and a chaotic milieu of different strands of early Christianity, some of which are barely recognizable to us today as Christian. One element of that forceful emergence of catholicity was, as I'm sure you know, the creation of a canon.
What I came to realize later was that I was taught the singular, nearly ultimate importance of the canon (the Bible), when in reality, what really bound the whole thing together was the
tradition that grew out of the emergence of a catholic faith; the canon was only one aspect. So it's almost this feedback loop where tradition venerates the Bible because of...the tradition that venerates it. The emphasis on the Bible of course could only reach it's modern heights once literacy was more prevalent, so of course, for hundreds of years, it didn't even play the role it does in modern Christianity. That's another example of the evolution of the tradition.
So it's true, as you say, that theologians sometimes have to do an awkward dance to fit Jesus into their theology; but in my mind, this is because of the underlying, sometimes unconscious, importance of
the tradition of Christianity itself. If there wasn't this need to remain tethered to tradition, theology might look a lot like secular philosophy; anything might be on the table. But tradition keeps theology chained to itself. Jesus is part of the tradition; he was the genesis (but not the founder, arguably) of the whole thing, after all. So he must be kept in. And gradually emerging doctrines like inerrancy and divine inspiration served to tether theology to tradition even more tightly.
A side note is that John's inclusion in the canon was controversial, and I think largely responsible for Jesus's role in the evolving tradition, and Paul was also important (but how many of the Pauline letters were actually written by Paul is another question). Sorry for the ramble, hopefully that made some sense.