No discourse (or idea-set) can have an ontological root other than the speaker’s life.
That assumes the discourse-maker as a complex being. Therefore, no discourse can be decoupled from the act-of-discoursing, that is, understood as something else than a real performed action.
Needless to say, then, every idea-set can only exist inside an specific circumstance. That is, every idea is itself part of a complex process.
In this sense, it is always possible to ask “why do you say so?” instead of “why is it so?”. The value of a discourse is solely derived from the life of the actor.
Therefore, discourses can not be completely right, nor can they bear Truth. We do not question whether Truth exists or not: in either case it would be futile for any discourse-maker to try to achieve absolute Truth — and this is a quirk in the communication process.
Idea-sets can definitely achieve a level of trust-worth that make it awkward to question them, but this is simply a methodological issue, not an epistemological one.
To stress: the amount of trust that a theory receives has no bearing whatsoever with it having Truth-ness.
To sum it up: all and every discourse must be met as an action, which must be dealt with as a complex circumstance, not as an autonomous system.
It doesn’t mean that you need to raise theological disambiguations when i ask you “bring me some water, please?” — but it does mean that you can raise them sometimes.
There is one last trap to be addressed. It goes like this: if every discourse has an “ontological root”, it might seem that being lends validity to any idea, or that the existence is the source of Truth (or any variations thereof).
The existence of the discourse is no more True than the discourse itself, though. The ontological circumstance of which a discourse is part is merely a context: it has the same “level” of validity than the ideas, and this level is the one we just said is no good guaranty for anything.