Is it possible to understand the beginning of Christianity without accepting the existence of a man as the "mustard seed" of the process of formation?
There are people trying to explain the beginning of Christianity as the mythical transplant of some god on to earth , an explanation attributed to Euhemerus, but even the greatest intelligence and expertise of a mighty biblical scholar has failed to explain much.
I prefer a religion based on a reformer of an already existing religion, who was perceived to offer a desirable change to some people, and whose basic ideas were developed into a new system by later generations. Or something along these lines.
The mania about interpolations, frauds, offending verses etc indicate the process of formation; those are amendments modifying the founding constitution of a new state.
Discussion about the New Testament, apocrypha, gnostics, church fathers, Christian origins, historical Jesus or otherwise, etc.