Your use of Christian I would take to refer to the religion developed by Constantine. We have only a very tenuous glimpse of early Christianity.
It's possible there was an awakened teacher who died too young to fully develop his followers understanding and that all that remains is a garbled misunderstanding that some people are trying to correct.
This is only one possible explanation of liberal Christianity. The religion that Constantine's politics developed is a blend of disparate and conflicting agendas but by virtue of its being the dominant to nearly exclusive religion of Europe for hundreds of years means that its nonsense is so deeply engrained in our culture that it has a validity bestowed by tradition.
Remember that the religion of Constantine ruthlessly stamped out diversity and enforced orthodoxy. But I'm disappointed that you would give this kind of claim to power any intellectual validity. Whatever you think about the gnostics, unitaritans etc. they were part of the early history of the church and though modern liberal Christianity includes a political correctness group there is more to it than that.
lfen