1 Thessalonians23
4 May the God of peace himself make you perfectly holy and may you entirely, spirit, soul, and body, be preserved blameless for the coming of our Lord Jesus Christ.
I suppose that would be the Biblical evidence of the triune nature of man.
Bibically speaking again, the distinction between soul and spirit is made in this passage as well, the implication here (possibly) being that the distinction is between the substance of the heart, or the substance of the mind:
"The word of God is living and active. Sharper than any double-edged sword, it penetrates even to dividing soul and spirit, joints and marrow; it judges the thoughts and attitudes of the heart." [Hebrews 4:12]
The controversy of course becomes whether the words 'spirit' and 'soul' refer to somethings essentially different and distinct, or whether the two words are placed in contradiction to each other to emphasis their essential sameness, and how sharp must be a truth that can divide them.
There is nevertheless something within our human experience, in which our understanding of what is right opposes our natural desires which speaks of an inner pyschic turmoil.
Now if our basic attitude is one of dualism, this tension between the carnal self of the natural man becomes identified with the body, as opposed to the spirit that now becomes identified with God.
The problem with such a conception has tended to be a Christian loathing for the body, and especially our carnal sexual desires. 'Flesh' in such a way of thinking, is no longer looked upon symbolically of figuratively anymore, but the battle becomes against the actual flesh.
This attitude is seen so clearly in some theologies in which our healing is linked so graphically and directly to the bloody scourging of Jesus. The more that the body of Jesus is meditated upon as being torn to bloody ribbons by the viscious scourging, the more our healing from the flesh becomes accentuated in this theology.
This, I believe, does not reflect the true Gospel.
There is a usefulness then, in placing the battle between good and evil more on the sphere of the inner man and our innter turmoil, lest it is our very created bodies that are identified wiht evil and sin.
But to the extent that it is our intellect that now becomes the white knight rescuing us from our baser, irrational emotional selves, we now are entering into the sins of the enlightened modern man. Reason becomes the new idol for this man, and it is his emotions that must be controlled and subordinated to the intellect.
In the end, this is merely a different kind of dualist thinking, in which our emotions become synonymous with our the carnal natures of our flesh, and again it is our 'emotional' carnal flesh that is being opposed
In summary, an understanding of our human nature that results in the disdain for our flesh that occurs when body is opposed to soul, can therefore lead to a false understanding.
And conversely an understanding of our irrational emotional/carnal faculties as needing to be subordinated to our intellects can likewise lead to the same false concepts of who we are.
One of the challenges of we post-moderns then, is to come to a better understanding about the nature of man.
To the extent that the triune categorization remains Biblically based in the fullness of scripture though, where the terms for spirit and soul are seen to be used interchangeably, the triune concept may yet be of value.
For as long as our triune differention is not between spirit(mind) and soul(heart), but between Spirit and spirit, or between Soul and soul, Gnostic denigration of God's Creation may yet be prevailed against.
For when the challenge of sin and evil is confined to the spiritual plane, and with our physicality sacramentally being given over to the glory of God through the Church, our bodies become the actual Temples from which the glory of God shines trhough.