I'm struck by two thoughts regarding Paul.
1. The mission he embarked upon after being met on the road to Damascus by Jesus was a total contradiction of his entire life up to that point. Isn't it odd that there would be a complete 180 degree turnaround by a man who was in a powerful position in the heirarchy of the Jews? What did he have to gain by that? I see loss of stature and trouble. By associating with gentiles it would be an anethema to him. Why would he do that? And of course, he did not have the fancy clothes, a 1st century equivalent of a private jet, nice hair and a tacky looking wife weighed down with 30 pounds of makeup.
2. There is not one of us today who has ever seen Jesus in the flesh or in any other manifistation that I am aware of. Does that mean that it is any more troublesome to believe that Jesus existed because all we have is the Scripture to verify His existance with respect to who He is as we do Paul?
I suppose if one doesn't believe the Scripture to be God breathed, that He wrote Scripture by inspiring people to write what He wanted, how He wanted, in a timeless fashion that is understandable to all at all times, then it seems pointless to argue the question.