Absolutely, "don't believe everything you think" ;)
I actually aim to have no beliefs at all, since I know they are counter productive and are mostly just guesses. I aim for knowingness and to do that means being fully accepting that it's ok not to know ;)
It is very wise to accept that it's ok not to know. The majority of humanity, I fear, is completely unwilling and perhaps incapable of coming to that conclusion. Unwilling and incapable because of pride, arrogance and narcissism. From my experience, most people are just not willing to admit that they are wrong about something.