Well, he certainly knows better now!
Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; By which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain. For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; And that he was buried, and that he rose again the third day according to the scriptures: And that he was seen of Cephas, then of the twelve: After that, he was seen of above five hundred brethren at once; of whom the greater part remain unto this present, but some are fallen asleep. After that, he was seen of James; then of all the apostles. And last of all he was seen of me also, as of one born out of due time. - I Corinthians 15:1-8
If one of Paul's contemporaries wanted to challenge him, they could easily disprove his statement that there was a large number of living eyewitnesses. One of the best validations of the historicity of the life, death and resurrection of Christ is the impact these events had on the lives of those who witnessed them. They went to their deaths rather than renounce the Truth they had witnessed.
Exactly. And likewise for the first claims of the resurrection. Where were these claims first made? In one place only on earth - Jerusalem. There were plenty of people there at the time (including Paul, f/k/a Saul) motivated by the desire to abort Christianity right in the womb, and all any of them had to do to disprove the claim of the resurrection was to walk over to the tomb and produce the body. They never did, and the earliest polemic of these enemies of the proclamation of the resurrection contains the tacit acknowledgment of THE EMPTY TOMB .
Cordially,