One of the reasons that it is so important here-and-now (it was not always thus) for Modern Man to recognize that all possible knowledge relies on fundamental (metaphysical assumptions) that ought-to-be intuitively endorsed -- is that otherwise we can be so dishonest with ourselves, that our entire belief-system becomes distorted and incoherent.
A specific instance is my own - pre-Christian - decades-long belief that death brought a total annihilation of body, mind... everything about a person. Any suggesting of anything personal (or a soul or spirit) that survived death - was blocked as obviously as wishful thinking.
The dishonesty was that I actually had some such assumption myself. If I was honest with myself, I assumed that at least some people in some way continued after death.
But, because I regarded this as wishful thinking; I dishonestly denied this conviction of mine.
Another example was about morality. As is very common, I would come across people doing some thing or another to themselves; which my official utilitarian secular ethics said 'did nobody any harm' - and therefore was not-wrong...
And yet - if I was honest - I could not shake-off the intuitive conviction that it was wrong. I assumed (wishfully?) that my own moral sense in this instance was merely socially-inculcated, and therefore meant nothing.
Therefore, I dishonestly denied my own unshakeable moral conviction that this particular self-act was wrong; at the price of obliterating the validity of all my moral convictions.
Because, after all, why had I assumed that acts done-to-oneself were necessarily morally neutral; whereas acts done to others were the sole proper domain of morality? What was that principle based-upon?
Was it not just-as arbitrary, just -s socially-inculcated, to say that morality was only about acts affecting others, as the unshakeable feeling that private acts were morally significant?
You see how dishonesty-to-oneself is used to deal with moral incoherence, with value=-incoherence in general?
And perhaps you also see that all values eventually reach a terminus at which we each, as individuals, must make an 'intuitive' evaluation, about what we personally regard as Good and True?
That our values are always, at root, our own responsibility - and that attempts to deny this are dishonest?
And perhaps, too, you may see how corrosive to Good and True values it may be, when one tries to deny this; that people can only deny it by lying to themselves about themselves - and how doing this will always have destructive consequences that will tend to ramify under-cover of this dishonesty?
Note added: Dishonesty with oneself is commonest among the mainstream materialist ideology of the West; but is also found among those who are "lifestyle religious" - those who regard the Main Thing about religion as being particular behaviours.
Further note: Honesty must be distinguished from 'doubt'. There is a state of modern 'doubt' that paralyses and causes despair. It often seeks relief in dishonest certainty; attained by surrender to arbitrary external authority - that is: from expediency masquerading as conviction.
But doubt may also lead to simple despair, and a desire for self-annihilation. It is therefore vital to realize that honest conviction rooted in fundamental intuition is distinct from 'certainty' - especially when certainty is assumed to entail something-like 100% correctness with zero possibility of error.
The search for such certainty as pre-condition for 'belief' - the insistence upon a situation clearly impossible in this mortal world - is a chimera; a trap set by evil.
Yet while certainty is indeed a snare; solid conviction sufficient to live - or die - by; is attainable by anyone who is honest with himself, and who pursues his surface beliefs to their intuitively-endorsed roots.