If both theory A and B make the same prediction X. Then finding that X is the case doesn't make either A or B more probable. Right? How does that not make any sense?
IN the case of Jesus historicity though, the theory has been found to be malleable, thus it loses its predictive power. Let me explain.
Before one tries to figure out whether there was a Jesus or not, I think one should first make sure that one's logic isn't a total mess. And it seems to me like MrMacSon's logic is a mess so I think one would need to address that before discussing the historicity of Jesus.