For the sake of the argument, let's take the historicity of a Jesus of Nazareth who was revered as the messiah and got executed by the Romans for granted. He lived, he preached, he died, and his followers turned his death into the spark of a new faith.
Still , that does not turn the miraculous events attributed to the man retroactively into historical fact. They are just as unsubstantiated as the belief that Mohammed traveled to Jerusalem and the heavens on a miracle steed, that the historical Buddha emerged from the womb capable of speech and sprouting flowers in his footsteps, or that Joseph Smith could translate foreign languages with the help of a seeing stone (just to mention a few).
There is *nothing* substantiating the virgin birth or the risen saints walking the streets of Jerusalem on the day of the crucifixion, earthquake and eclipse included. The case for all of these supposed events is exactly as weak as that of other religions.