They claim to know the truth but the reasoning behind it is different between religions. I'm no religious expert but I'm very familiar with Mormonism and they push really hard on the idea that faith is intentionally separate from truth and you learn about the truth of the church by meditating on your feelings and experiencing frisson, not via logic. Yes everyone has their mythology and Mormonism has its share of things the prophet says God says but it is very different than the Christian apologists that try to reconcile the Bible with things like astrophysics and other observed phenomena.
Do you have a citation for this? I am reasonably familiar with Mormonism (The Church of Jesus Christ of Latter-day Saints) and I don't think I have ever heard this before?
I'm no religious scholar but I've had a LOT of conversations with Mormons with various levels of training (regular folks, bishops, missionaries) about why parts of the story don't make logical sense or aren't internally consistent. The common answers are in the expected range from the standard "god works in mysterious ways" to "if you could prove God was real it wouldn't take faith and the point of the human existence is to find faith".
The Mormon church, of course, has its wings of scholars trying to find evidence to support their origin stories (like looking for their god's original home planet or buying ancient South American temples to hopefully find something supporting the story of white peoples in the early Americas) but they also fully lean in to the idea that humans are inherently fallable and human reason isn't as powerful as faith and feeling. I think this is well demonstrated by the ritual of "bearing one's testimony" in church which is always ways you FELT the holy spirit or by the modern forgiveness (and embracing of) the clear corruption and deception of the original prophet Joseph Smith (like the demonstrably false book of Abraham, for example).
This isn't even supposed to be judgement of one way over the other - I'm just describing the very strong difference between Christian apologists like the author (who want the true truth the right way) and other kinds of proselytizing (that are more supportive of "any road to the right answer").
It still seems like a meaningless distinction, Buddhism also rests on claims of real world events: the Buddha is a historical figure, the story of his enlightenment being a factual happening is key to the belief system.
There are ways of interpreting and practicing Buddhism in which this is less important (eg modernist, psychological, western), but that's also true of Christianity (eg the Jefferson Bible, Unitarians, etc).