Vitium est omnia credere, vitium nihil credere.
(Pseudo-Seneca)

Pron = WIH-tee-oom ehst OHM-nee-ah KRAY-deh-reh WIH-tee-oom NEE-hill KRAY-deh-reh

It is a vice to believe in everything, and a vice to believe in nothing.

Comment: This proverb asks us to find some place between extremes:
the extreme of the gullible who believe everything and the extreme of the cynical who believe nothing. I will throw one more distinction into the mix. The Latin word "credere" can be translated both as "to believe" and as "to trust". I am not convinced that belief in anything is necessary. To be asked to believe something requires me to accept as real and true a thing for which there is no evidence, no relationship and no experience. Further, with regard to religious or nationalistic "beliefs", I am being asked to accept someone else's judgment on a thing without my own evidence, relationship or experience.

Trust may be a little different in that it implies a relationship, and
that adds an element to the human experience that belief does not.
Within a relationship with a human being or with nature, even, I will have my own experiences and evidence for deciding whether to trust or not. It is still a precarious thing, though. My trust may be violated. My experiences may be painful. But the evidence will be mine, and then I may navigate in life who and what to trust, who and what not to trust.

And that leaves some place between trusting everyone (dangerously
gullible) and trusting no one (dangerously isolated).

The wisdom of this proverbs advises us to avoid both extremes.