Belief and Knowledge?

I understand that people use the word "believe" when they are somewhat but not entirely sure of a proposition …..e.g. "I believe that she can sing well", as opposed to "I know that she can sing well"…….So, if a person "believes" does he “know” the proposition? Is there a degree in the “belief” that allows “knowledge” like the hymn that goes’ “I know that my Redeemer lives”?