should you believe only what you see?

Let's keep it simple. I have not seen god :D
But ask me "do you believe in god?"
I will say "yes".
You may find me stupid for believing on something I can't see.

Generally we don't believe on what we can't see and thus it can be said that we only believe what we see. But is "what we see" the only truth? Can we rely so much on our vision?

If I am to believe what I see, then Sun rises in the east and sets in the west. Sun is moving in the sky around the earth. And in the night, I can see a huge moon and small twinkling stars and I conclude "moon is bigger than star". Being student of science I know both of these facts in this paragraph are false. But if I only believe in what I see then these things must be true! But I will be called stupid if I believe in such things!

So now I am wondering, who is stupid? the one who only believes what he sees or the one who believes even the things he does not see.

Now I also remember a story;
Once a boy was asked by a teacher:do you believe in god?
Boy: yes
Teacher: Have you seen god?
Boy: No
Teacher: Then God doesn't exist.
Boy: Excuse me sir, can you see your own brain?
Teacher: No.
Boy: Well, then it doesn't exist.
(whole class laughed)

You too will be laughed at, if you think you should believe only what you see :D