Indeed, metaphysically insanity is the only true madness - it is the madness of having false assumptions about the basic nature of reality.
Modern man is sure of only one thing: that there is no God. That is why he is insane - because this metaphysical assumption leads to nihilism (unbelief in reality).
Once he is unsure of anything; he loses all possibility of a scale of judgment: so modern Man utterly believes things that not only aren't true, but cannot be true - and what is more he knows they are not true and cannot be true - but he believes them anyway (sort of) because, ultimately, nothing is true.
And he disbelieves common sense and his own experience because, after all - he might be insane, deluded, hallucinating... indeed Modern Man knows, deep down, that he is insane.
And therefore he cannot believe anything - or rather, he can disbelieve anything; no matter how obvious, no matter how much evidence or logic agrees with it.
Modern Man knows he is insane because he knows that he has made himself insane - by choice, by choosing to be sure of only one thing: that there is no God.
Therefore, Modern Man is completely to blame and responsible for his condition and situation - he initiated and perpetuates it; and fights tooth and nail to retain his insanity against the hourly onslaught of counter-evidence, rationality and basic conviction.
He could change at any moment in the twinkling of an eye - but he does not. So this is a moral insanity - insanity based upon evil.
The basic answer (not the complete answer - but the necessary start) is itself very basic - acknowledge the reality of God, of Deity.
Nothing else will suffice. Lacking it, all the rest is not merely a waste of time but ever more deeply insane.