"Believing in someone." That's a weird phrase, isn't it?
After all, if you truly believed in a person, you wouldn't need to say, "I believe in you."
It's like saying, "I believe in air." You mean "beleiving" because there's doubt?
I don't mean to say that "believing in something" is like a lie.
"Believing" is really a term of hope of wanting to believe.