Near the beginning of my walk I thought of a more apt phrase for my prior comment: replace "the cacophony and empty chatter of the world" with "the shrill cacophony of the theological marketplace." Further along the trail I wondered how many OST readers have witnessed the beauty of a high prairie liberally dotted with the surprisingly gaudy yellow blossoms of low-growing cacti.

And yes, I also thought about Colossians 3. We veer farther afield by considering the broader Pauline themes of morality, the law, justification, and sanctification, but we must address them at least cursorily in the context of the "new man."

For you have died and your life is hidden with Christ in God. When
Christ, who is our life, is revealed, then you also will be revealed
with Him in glory. Therefore consider the members of your earthly body
as dead to immorality, impurity, passion, evil desire, and greed, which
amounts to idolatry… But now you also, put them all aside: anger, wrath, malice, slander,
and abusive speech from your mouth. Do not lie to one another, since
you laid aside the old man with its evil practices, and have put on the
new man who is being renewed to a true knowledge according to the image of the One who created him. (Col. 3:5,9-10)

In Romans 6:2 Paul says that he died to sin; then, in 7:4, he says he also died to the law, in order that he might be joined to the resurrected Christ. Paul repeats this thought in Gal. 2:19: I through the Law am dead to the Law, that I might live to God. Now, in Col. 3, Paul tells his readers to consider themselves dead to sin, but in the prior chapter he told them that ascetic self-denial wasn’t of any value. So which is it: dead to sin or dead to law? The general message is something like this: neither obedience to the law nor disobedience, neither self-denial nor self-gratification, will bring you into the life of God. Both of these seemingly opposing attitudes are part of the same dead thing; namely, "the flesh."

For the mind set on the flesh is death, but the mind set on the Spirit is life and peace. (Rom. 8:6)

Reading this translation one might think that Paul is advocating an Aristotelian (also Watchman Nee) tripartite division of the self into body, soul, and spirit: the soul (or mind) can focus on bodily lusts, which lead to death, or it can turn its attention to spiritual things, leading to life. But here is a more literal translation of that same verse:

For the flesh’s way of thinking is death; but the spirit’s way of thinking is life and peace.

The flesh and the spirit are alternative ways of thinking, of orienting oneself to reality. The orientation called "the flesh" is concerned with the old-creation distinctions between Jew and Greek, and it is simultaneously obsessed with achieving justification through obeying the law and with succumbing to the desire to break the law. This fleshly orientation is death, so Paul tells his readers to die to this death-dealing thought pattern: death to the distinctions between Jew and Greek, death to law, death to sin. Instead, Paul encourages his readers to adopt the alternative orientation toward the world called "the spirit." The spirit is concerned with other matters: knowledge and wisdom, peace and compassion, kindness and forebearance, God, love, life.

I think we probably agree more than disagree here, Peter. You say:

"Paul’s emphasis throughout the passage is on what has been
accomplished through Christ for believers now, rather than how it will
be in the future. Remarkably therefore, we are described as already raised (from the
dead), and already seated with Christ where he is, our lives being
already ‘hidden with Christ in God’."

Yes, that’s right. It’s not through setting aside the sinful life that the believer is gradually transformed into a good person. When considered from the perspective of the spirit the believer is already good.

"So Paul is describing the means of living a holy life."

I don’t think that’s true. Setting aside the unholy life doesn’t provide the means of living a holy life. If that were true, then following the law would lead to holiness. Paul insists this isn’t the case: consider yourself dead to the law and any expectations you might still entertain that through ceasing your immorality and behaving well you will become holy. Dying to unholiness isn’t the same thing as living in holiness. The one is part of the continual dying to the old man; the other results from the continual renewal of the new man.

"…union with Christ is described as a living reality.
This is the ‘new creation’"

Agreed. This living reality is participation in Christ’s resurrection life. Death to the old life, the flesh, the old man, the Jew-Gentile distinction, the law and sin — this death is inevitable and not to be resisted. The new creation is something else altogether: a subjective partipation in the subjectively-experienced event of Christ’s resurrection. Ultimately it’s living in the new that’s Paul’s main concern throughout his letters.