I was asked this question and I submitted this answer. The asker came back happy and thanked me for it. So am sharing my reply to more people.
As for his existence and death, these three things agree:
- Eye witness accounts of gospel writers (Matthew, Mark, Luke, John),
- Credible and famous historians whom we trust with other data about the ancient world confirmed these accounts (Pliny the Younger is a Roman historian and governor; Flavius Josephus is a Jewish historian who became a member of the Roman aristocracy; Tacitus was a senator and historian of the Empire),
- Archaeological data including the latest findings confirm all the above (actual locations of Calvary and the Sepulchre among other things). If only one archaeological finding confirmed the existence of Troy, once thought to be a myth, what more the abundance of Christian archaeological sites?
As for his actual death, we can add to the above the fact that his executioners were Roman soldiers. They were the best soldiers of antiquity who knew the business of killing.
As for his actual rising from the dead, we can add the daring and boldness of those who preached about the Resurrection, and about seeing him alive. (The gospel reports 500 who saw him after death).
If they were creating a myth or had certain doubts, the great number of Christian martyrs would not have died for their belief-- for what they saw.