It's pretty plain that when people say they believe in something they don't neccersarily see it before them or in the past - nobody bothers to say I believe in dogs, for example, but are super keen to say they believe in gods - which they probably haven't seen.

Wikipedia parses the meaning of belief into 2 categories. Not that categorisation can neccersarily be defended in any meaingful way until it because ''incorporated by obliteration '' into scientific literature.

'

Commendatory - an expression of confidence in a person or entity, as in, “I believe in his ability to do the job.”
Existential claim - to claim belief in the existence of an entity or phenomenon with the implied need to justify its claim to existence. It is often used when the entity is not real, or its existence is in doubt. “He believes in witches and ghosts” or “many children believe in Santa Claus” or “I believe in a deity” are typical examples.[13]

''