Idealist or spiritual truth even as it comes close to or perhaps attains self-grounding, can never have the kind of certainty that objective truth has that is verifiable by anyone and independent of any knower. Subjective self-certainty can always be opposed by an other subjective self-certainty, there is nothing to mediate them equally on their own grounds. And yet this is the kind of truth that you seek which can never make good its claim to be a final truth, no more so that ordinary objective consensus truth. Both are shadowed by skepticism, but wile the latter sits easily with it, the former does not.