What seems to emerge is this:

1. There was a itinerant Rabbi named Yeshua who lived in Galillee between about 5 BCE to 30 BCE. He may or may not have claimed to be the Davidic messiah.

2. He founded a Jewish sect, such as the Quram community, the Essenes, and others of the period.

3. He was crucified by the Romans, probably for setting himself up as the King of the Jewish Nation.

4. After his death his followers scattered, probably to Galillee, and later regrouped. From there they had power grabs, theological spats, and schisms.

5. Paul (nee Saul of Tarsus) ramrodded his ideas through, remaking the original Jewish sect into the seed of what we now call Christianity.

That Yeshua probably existed is all but certain, since many people wrote down what they think he said, did and taught. The rest of it becomes matters of Faith.