Disbelief, if not held TOO strongly, can be overturned by observation of evidence. However, there are plenty of people who can ignore or rationalize anything (it's called cognitive dissonance, or pure stubbornness). Either extreme-- superstitious gullibility or blind fanaticism*-- is bad. Science means keeping an open mind.

*Have you ever noticed how closely related these two are?

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort