Since we are each entitled to our own beliefs but not to our own facts, it follows that beliefs are not facts. Yet beliefs are valuable and inevitable. More on this later.
Since beliefs are not facts we do not measure beliefs on a scale of true or false. Instead we measure beliefs on a scale of sound or unsound.
How do we distinguish sound from unsound beliefs? Sound beliefs produce kindness. Unsound beliefs produce unkindness and cruelty. So it is as it was written in an ancient text of wisdom, we know them by their fruits.