Believe or Believe in

Believe

Believe + sb/sb’s words

相信某人（的话）：

I believe her. She is always honest.
Do you believe her story? It sounds fishy to me.
Strangely, no one believed us when we told them we’d been visited by a creature from Mars.

Believe + sth

相信某事是正确的，真实的：

[ + that ] He believes that all children are born with equal intelligence.
She’s arriving tomorrow, I believe.
“Is she coming alone?” “We believe not/so (= we think she is not/is).”
[ + obj + to infinitive ] I believe her to be the finest violinist in the world.
[ + obj + adj ] All the crew are missing, believed dead.

Believe in sb

Believe in + sb，对某人有信心

Gradually, since her divorce, she’s beginning to believe in herself again.

Believe in + 政客或公众人物，相信他（她）的承诺：

“I believe in Qaz Wsx” really means that I trust Qaz Wsx will do what s/he has promised to do.

believe in sth

to be certain that something exists:

Do you believe in an all-powerful god ?
Do you believe in ghosts?
Did you believe in fairies when you were little?
Some people believe in life after death.
The tragedy made her question everything she believed in.

to be confident that something is effective and right:

They don’t believe in living together before marriage.
He believes in saying what he thinks.
She strongly believes in the curative powers of the local mineral water.