Starting with Paul who wasn't a witness to the crucifixion writing 25 years later, we hear that Jesus was seen alive by 500 people (before his "Ascension"). Unfortunately, Paul wrote this to the Corinthians 800 miles from Jerusalem who who would not be expected to have first hand knowledge. He did not write to any Romans.
But curiously although Jerusalem at that time had many literate Hebrews, Romans, Greeks, and others, and this fantastic story would have been widely spread, there are no written reports about it. Nor is this alleged appearance to 500 reported in any of the Gospels.
The Gospels were written by non-witnesses between 70 and 95 AD.
Is Paul's really a fictional story that caught on later? The purported ascension made verification impossible. Maybe that's why it had to be written as it was.


