Belief in the psychological sense, is a representational mental state that takes the form of a propositional attitude. In the religious sense, "belief" refers to a part of a wider spiritual or moral foundation, generally called faith.
belief (plural: beliefs)
Mental acceptance of a claim as truth without evidence.
(countable) Something believed.
The ancient people have a belief in many deities.
(uncountable) The quality or state of believing.
My belief that it will rain tomorrow is strong.
(uncountable) Religious faith.
She often said it was her belief that carried her through the hard times.
(plural) One's religious or moral convictions.
I can't do that. It's against my beliefs.