In a certain sense, although man has "a nature," it seems to me that he is unclassifiable, as you suggest and for the reasons you suggest, Pietro. Man is simultaneously in one sense "motion," and in another sense "essence," or perfect "stillness" (I think the latter is how God, Who knows all things completely, sees us).
In other words, as the Greeks would have it, man is simultaneously "becoming" and "being." I guess this is the deal man gets for existing at the "intersection of time and timelessness," the preeminent quality of man as mediated by the soul.
On a different level, the analogy to man you give in the particle/wave duality of the physicist is a very apt idea -- two complementary aspects of a single phenomenon, the choice of which to consider being wholly in the "eye of the observer."
Thus depending on the observer, man can be "this" or "that." In other words, the observer will see what he's looking for -- yet neither the "particle" nor the "wave" aspect is a complete description of man.
Plus some observers, in viewing man, may "observe things" which are neither "particle" nor "wave," but some other construct that isn't "there" at all. Call this a type of psychological projection maybe. To expect to find a complete description of man in general or in the particular on the basis of any discrete observation is bound to be a reductionism. (Yet people have been known to make entire careers out of a reductionism like this.)
Man truly is an amalgamation of the glorious -- and the abject, of the saint and the sinner. He lives in the tension in between time and timelessness, the depths and the heights of the soul; and I believe that in that "oscillating" tension, the more man "eccentricizes [his] oscillations towards God the more resonance [he] finds in reality," and particularly the reality of what he is, in himself.
I wholly agree with you that the more we look to God, the more God reveals to us -- and that revelation is God's perfect Truth.
That's really false ... mirror --- reality check ?
One simple difference for Christianity ... if you go the way of Jesus Christ --- you won't have any self righteousness (( works - evolution )) left !