Given the various comments and discussions generated by my first post on this topic and some new developments of thought, I'd like to expand on what I said towards a more practical appropriation.
Part of the difficulty is that whenever we speak of the "two natures" or "hypostatic union" of Christ, the discussion quickly gets railroaded by philosophical problems. What is the "divine nature"? What is "human nature" (this one is especially tricky now that the NIV -- amongst others -- has unhelpfully made the flesh to be the essential 'sin nature' of man: another reason to avoid that translation, I suppose)? How does these things relate to discussions of "substance"? In the life of the Church, important as these questions may be, many believers' eyes roll into the backs of their heads and they wonder how Christian doctrine can be so (1) boring and (2) impractical. In the last post, I tried to spell out how our union with Christ (our own "hypostatic union" as it were) is effected and made actual through common worship. The question was raised: what about the time we aren't in common worship? This is where a discussion of nature is helpful.
Whatever else "nature" may be, it is the record of action. A human is what a human does. God is as we see Him working in creation and redemption. So, if we are becoming more and more "conformed into the image of the Son" (Rom. 8), it means that we are doing the work of the Son. This is vitally important. We often act and believe as if Christ did his work on earth and ascended and basically is done working until the Second Coming. However, if we believe that the Father and Jesus share the Spirit, and that the Spirit has been poured out on "all flesh" (Joel 2 and Acts 2), we believe that God through the Son and Spirit is still working -- in fact, He is the primary actor in history (even today), and we join His work. All our work, whether the work of worship (we join in the worship by the Son to the Father; the Father blesses the Son and all those united to him) or our daily vocation, is the work of Christ: he is building his Kingdom, he is beautifying his Creation, he is bringing peace and release from all the effects of sin. So, whatever our work is, should be patterned after the work of the Son: we are, after all, "seated" (that is, enthroned) "with him in the heavenly places" (Eph. 1). This can give us great comfort, that we are not only not alone, we are not the instigators of the work, Christ is. However, if our work is to be a function of his reign, then our work -- whatever it is -- needs to take on the character of his action (or nature). What is Christ's nature? The Gospels make it clear: he is the compassionate One, the One who seeks out the poor, the lame, the blind, the outcast, the leper, the sinner and calls them to repentance and cleansing. He is the One who confronts power and privilege with the Gospel of self-giving, calling all the rich and comfortable to share with those who are united to him, building up one Man, one humanity that differs from the old, adversarial way of being (Gen. 3).
Is our work, our daily theosis (whether this be a "job," raising a family, being a student, etc.), following this pattern? Or are we "conformed to the world" whether it is in needing the right pay-scale or the proper amount of vacation days, or even being too far away from parish or home to be of any service to the poor, outcast, or sinner in our midst? The reign of Christ will change us (remember, it is his work!), but he has graciously called us to repent of the old forms of life, whether outright pagan or the "American Dream," so that we might join him in his work freely. So, it is not just common worship, but our common life in our everywhere places that show forth this active work of God's Spirit (His very Life!) and how we look, from glory to glory, more like the Son who has saved us and is redeeming the world.