1. Romans (cf Rom 15:1-7) - We are justified by faith (and not by circumcision, etc...) and should therefore act as the unified whole by being 'in Christ' (especially by taking part in his suffering for the sake of each other).Afterwards, another brother came up and thought that I may be emphasizing unity too much (kind of like saying, 'it's all about love' or 'it's all about peace'). Here I had to both agree and disagree. I agree that unity is a common theme because it plays a key role in the common story, so it comes up again and again. But, in another way I disagreed, wanting to say that these letters were written to church's in the explicit hope that they would be unified in Christ. The incarnation might crop up again and again (Christian metaphysics?), love might be all over the place (Christian ethics?), and peace is quite common (Christian aesthetics?), but this doesn't mean that they're all the same thing.
2. 1 Corinthians (cf 1 Cor 1:10-13) - Acting 'in Christ' means acting in the full knowledge and hope of our own resurrection (see 1 Cor 15), guaranteed by his own (notice that this resurrection implies action in verse 58).
3. Galatians (cf Gal 2-3, especially Peter's sin in 2:12) - Justification by faith directly implies that our fellowship, that our sharing of communion, that our unity is demonstrated (guaranteed?) by our faith, not by our circumcision.
4. James - This implication must be carried out (you can't just say that we are unified, you must do it), whether it means sitting by the lowly in church (Ja 2) or teaching wisely and carefully in church (Ja 3) leading to wisdom with peace and without partiality (very unifying characteristics, I must say).
Ok, this is all to get to another point, namely that of authority. Earlier, I had suggested to brother #1 that authority exists because of unity. Let me explain, I think that the reason only clergy (elders, priests, whatever) should give the Eucharistic meal is that they are the focal point for what brings that particular group of people together. They are the closest thing we get to true unity in the local church. As such, the meal that is all about that unity (remember Galatians) of the church should really be given by the symbol of that unity. We should also remember the whole heresy of Donatism, which says (from my ver limited perspective) that the effectiveness of the sacraments is not based on the moral quality of the person giving it. In other words, it's the position that matters, not the minister. For Protestants who are uncomfortable with this, think about wisdom that you get from preaching; is the wisdom not from God (or less so) if the minister is in sin? If you accept this, then it gets a little bit easier see that the priest or elder or whatever is acting in personae Christi (I probably spelled that wrong), not because he is granted this authority from the eldership (or another ruling council), but because he is the acting as the unifying factor of a particular community that is 'in Christ'.
Finally, then, we can start to see a bit more clearly our own roles in the body of Christ stem from this unity, which sees other roles in the body of Christ besides teachers (1 Cor 12). And I know this might seem frightening to some TULIP-ists, but it also demonstrates that it is possible for us to act outside of our own particular roles within the community. At these times, we are not acting 'in Christ' (under his Kingly rule) but under our own. But at the same time, he has taken those times that we have strayed from his rule via his representational role as King (see the Old Testament, what happens to the king happens to the people and vice versa), was crucified and was then vindicated. As long as we remain within his people, we are promised the same vindication, the same resurrection after we are judged before the throne. How do we know we are his people? I'm not as sure about this part, but I think we recognize this in ourselves and in each other by faith (see Romans) giving us assurance of a favorable judgment (thusly suggesting Rom 10:12-13) though something about the Spirit's fruit and the sacraments (specifically baptism and the Eucharist) might also be suggested, but also definitively meaning that we will act in love, fulfilling the law and thusly receiving the favorable judgment.
Sorry, I know this is rather jumbled, but I though the whole thing about acting out our own unifying positions (known via our gifts) in the church (and thusly in the kingdom), correlating to elders/priests acting out their own unifying roles, as a source of ethics/ecclesiology was pretty darn interesting. Thoughts...?