The fictitious galaxy that makes up the
Star Wars universe is vast and diverse but no matter where its fictional inhabitants go, there will always be one consistency:
the Force. When describing what exactly the Force is to a young Luke Skywalker in the original film, Jedi Master Obi Wan Kenobi defined it as "what gives a Jedi his power. It's an energy field created by all living things. It surrounds us and penetrates us; it binds the galaxy together."

For decades, fans of the Star Wars franchise remained confident that the Force is a religious entity that defied the laws of science. In the original trilogy, certain characters describe the Force as an "ancient religion" that was followed by the Jedi. Many characters didn't even believe it existed. The perception of the Force being a mystical power lasted until a somewhat controversial scene in 1999's Star Wars Episode I: The Phantom Menace, which involved a Jedi named Qui Gon Jinn explaining to a young Anakin Skywalker what the Force is. The scene is reminiscent of the one used in the original film but with one major deviation: Qui Gon Jinn provided a scientific explanation for the Force.
This inevitably led to much confusion among viewers. If there is a scientific explanation for the Force, then why do characters treat it as a religion in the original trilogy? The time gap between the prequels and the original films is much too short for the idea of the Force to fade over time. While this could be written off as a simple continuity inconsistency, I think there also a perfectly logical explanation. What if the Force fell into public skepticism due to imperial propaganda?

Throughout the franchise, the Galactic Empire has been known to use propaganda as a means to an end. For example, in
Star Wars Episode III: Revenge of the Sith, Emperor Darth Sidious created fabricated lies of an attempted Jedi mutiny in order to justify wiping them out. In the canon video game,
Star Wars: Uprising, an imperial governor completely shut down his space sector in order to convince the population that the Rebels didn't destroy the second Death Star and momentarily win the war.
When the Empire began exterminating the Jedi in the prequels, they obviously did so with the intention of having them stay dead. However, ending the current Jedi population does not stop more Force sensitive beings from popping up around the galaxy. Therefore, it only makes sense that the Empire would want to suppress the perception that the Force is a fact by having people question its existence. As seen in the original film, it worked rather well, as even members of the Empire themselves didn't believe in the Force. As for the Force sensitive characters who learned of their abilities, the Empire would either attempt to recruit them or give them the same fate as the Jedi.
Of course, we all have to keep in mind that this is just speculation on my part. Could the Force be the victim of imperial propaganda? Is this a simple continuity error in the films? Will we ever get an official explanation? With the Star Wars films making their return this winter, all we can do is wait and see.