Way back in the dawn of time, before apes and people were even different, the ape-people looked up in the sky and saw lightning storms, bringing rain. It inspired strong emotions; awe and wonder, thankfulness and fear. The ape-people recognized this was a force much greater than them, they wanted to know what it was, they wanted to express their gratitude to it for bringing the rain, and they wanted to be protected from it. They didn't know what it was, but like they did with everything else, they gave it a name.
They called it god.
Humans name things, it's what we do. Our biology lays out the rules, and one of them is to attribute agency to things. Today we interact with abstract forces as agents, like electricity, magnetism, even artificial intelligence, and we take them for granted, but back then there were no bodiless agents to model the unseen maker of lightning. They didn't look for a cause, then, but a maker, something they could visualize in terms of their own experience.
They experienced lightning firsthand, obvious to anyone. It's up in the sky, it destroys things, and it can kill you. It's invisible. It's way more powerful than anything any human could ever be. Obviously, there is somebody up there making it happen. That much is as logical as that the sun rises and passes over the earth every day. Some people insist the sun doesn't do that, but who should you believe, them or your own lying eyes?
So what we knew, then, was that this cause of lightning, this god is: invisible, way powerful, and dangerous. Beyond that, nobody could say much, but that didn't stop them from speculating. Everybody had opinions as to why this god-guy attacked some places and not others. People looked for the pattern, what it might be that all its victims had in common, what they did to make the lightning attack them and not something else.
If they could just figure that out, they'd be safe, and there's a ready market for people who claim they can keep you safe. All you have to do is what they tell you, and then if you weren't hit by lightning it proved their system worked: Do what we say → No lightning → Profit. There were plenty of buyers. There were also plenty of sellers, all fighting over market share, offering their own descriptions of the god and telling people what to do.
That's how things stood for thousands of years.
There were always troublemakers, though, poking around asking just how did this god cause lightning, and what was its exact nature? Eventually, after thousands of years, they figured out the answers.
This time, they not only told people what the lighting god really was, they showed them. The lightning god is invisible all right, but he's not a being, he's little particles and charges. There's not just one god, there's zillions, and this is exactly what they're like. Not only that, we can show you how to protect yourself from these gods. No sacrifices needed, just put up a lightning rod, give them a path to the ground, and they leave you alone. We can even make them do tricks for us, look: compasses, light bulbs, the telegraph. Woot!
This was a critical moment for humanity.
Up till then, they had a description of something: a meaning, and a name, “god”.
Just like they had a description of anything else: a meaning, and a name, “food”.
If they take one road, they accept the new description, give up their old wrong ideas of what god is like, build lightning rods for god as it really is, and progress into a bright new future. That would be the more honest path.
If they take the other road, they refuse to accept the new description and burn the troublemakers at the stake. When that didn't work, they adopted a new strategy and changed their definition. Instead of saying god is "what causes lightning", what they had been saying all along, they kept the name and took away the meaning. They gave another name to the description “what causes lightning”, and made up a new description to put with the name god.
For millennia, god had been the thing that caused lightning. Now suddenly, it didn't mean that anymore. It's as if they said what you eat is not food anymore, what you eat is rocks and dirt, and food is some imaginary substance. On this road, the thing that causes lightning is now electricity and god is now something else, something there is no evidence for. And they can go forward, down the road into superstition and stagnation.
Humanity came to that fork in the road. They took the road less honest.