Tomorrow cannot erase what is in one's brain.
People are in prison, whom have not seen a religious text, in decades. They haven't stopped believing in what they read.
A better hypothetical would be, if there was
never a religious text, in the first place, would humans even believe a global flood occurred within the span of human existence?
The answer would depend on man, and how thing "played out".
Would there be any recordings at all?
For example, would there be people who recorded any event in history? Would people only write myths? Why do myths exist, anyway? Did people just wake up one morning and decide to write a story, or are people writing stories based on their own experience, and what they see?
True, some do write things that are only imagined, but that is not how everyone writes. Some write what they actually know.
If nobody wrote what they actually know, then we only have what modern day experts tell us, from the research done through the study we call science... which isn't actually history, but a story itself, put together to fill in the gap that no one has ever recorded.
Would that not be myth itself?
For example, was there really a big bang?
The Myth Of The Beginning Of Time
String theory suggests that the BIG BANG was not the origin of the universe but simply the outcome of a preexisting state
Beginning in the 1970s, scientists started identifying some puzzles surrounding the Big Bang... There really was a Universe before the hot Big Bang, and some very strong evidence from the 21st century truly proves that it’s so.
The documents making up our Bible today, are actually recordings of events in history, by people living in the past. If we erase all recordings, and depend on people to use extrapolation, interpretations, inferences, assumptions, and ideas, it is quite likely we will live our entire lives believing something, but not knowing if it is the truth or not.
When we have records, which are a primary source of evidence, and secondary sources can verify it, we have something we can be sure of. That is better than explanations that are favored, which people.. including scientists themselves, question.
Records actually help archaeologist to know where to look, and this saves the taking hundreds of years to find answers... answers which may be wrong.
If no record of a global flood were made, people would have no reason to contend that there was, or there was not.