re: Why believe?
If someone never heard of or studied astrology and was asked if he believed in astrology, what must he answer ?
Why believe in anything when there's already so much to try to understand in the real world for our own good ? If a doctor presents figures and tells you something should be done, is it a "belief" we need to have or when we accept his arguments , what is this behavior? A belief, too?
If we only trust the real tangible things and don't care at all about anything "Superior", do we "believe" or don't we "trust facts and common sense" ?