It isn't often I can use a single piece to bring together communism, fascism, Islam and gnosticism, but there it is.
All of them assume it is possible to know all the truth, and here it is on this plate ~ take it.
Sorry ~ God, and "reality", continue to provide revelation of new things, new systems, new approaches to new questions or old, settled issues.
Notice that Islam argues that Mohammad was the LAST PROPHET and there will be no more revelations. Marx and the fascist theoreticians argued that there was an endpoint to Hegelian logic, and they knew what that endpoint was ~ no more thesis/antithesis.
Gnosticism argues that we can "know" with objective certainty.
Sorry ~ doesn't work that way ~ it's quite subjective all the way down, and new stuff just keeps popping up all the time. Today there's news of two supermassive blackholes in a distant galaxy preparing to collide. Billions of stars will be sucked into the new super-supermassive blackhole.
Maybe.
Still, we know this happened hundreds of millions of years ago.