“It’s an energy field created by all living things. It surrounds us and penetrates us; it binds the galaxy together.” - Obi-wan Kenobi
“I find your lack of faith disturbing.” - Darth Vader
“The dark side of the Force is a pathway to many abilities some consider to be unnatural.” - Chancellor Palpatine
“I’m one with the Force. The Force is with me.” - Chirrut Îmwe
"Hokey religions and ancient weapons are no match for a good blaster at your side, kid." - Han Solo
"Don't try to frighten us with your sorcerer's ways, Lord Vader. Your sad devotion to that ancient religion has not helped you conjure up the stolen data tapes, or given you clairvoyance enough to find the rebels' hidden fort-..." [sound of choking] - Admiral Motti
If the character believes in the Force, but is not a Force user, it could mean any number of things. Is the character jealous of Force users? Afraid of them? In awe of them?
If the character does not believe, how do they react to use of the Force? Are they dismissive, like poor Admiral Motti? Do they believe technology is superior? Are they uncomfortable? Is there sufficient evidence to change their belief?
In other words... there is no specific rules weight to a character's attitude towards the Force, but it can have significant impact on how the character interacts with other members of the group or the population of the galaxy.
Even among those who believe in the Force, there are different opinions on what the Force actually is - adherents of the Living Force have a different perspective than those of the Unifying Force. Game-wise, they select from the same powers, but what those powers mean (and which ones interest a given character) can be influenced by their beliefs.