It's the year 4024. In the past 2,000 years, civilizations have crashed, rebounded, and crashed again multiple times.
As yet another civilization declines and crumbles, a cult has sprouted that worships a "Super Man" from another world who performs miracles in order to save the people of Earth. He suffers like they suffer. He dies like they feel their society dying. Their Super Man is resurrected, just as they also hope to do.
This cult in 4024 is politically strong, but some people resent how the cult abused their power. So they attack the cult at the base of their faith, denying the very existence of a Super Man who incarnated as Clark Kent.
The cult is furious that they should dare be questioned. They insist Clark Kent was a real person who really spoke truth to power as a news reporter.
Of course there were Clarks who lived around the time this supposed Super Man lived. There were even several Kents. But the Clark Kent that the cult speaks of didn't enter the historical record until much after the time he supposedly worked for the Daily Planet. And those references were sparse at best, and merely speaking from the point of view of something called a comic book club.