You will find many claims in science and religious texts that this, that and the next thing is 100% factual and true. Usually, in science at least, those claims are backed up by hard evidence, peer reviewed, and published for the entire world to read and examine. However, that’s not always the case. Claims are sometimes made that such-and-such is factual, but there’s no supporting evidence, which a) wouldn’t be so bad if that were admitted, and b) if those failing to give their evidence didn’t demand hardcore evidence from others for their claims.