I don’t have time for much today, as I’m about to head to New Orleans, but I couldn’t help but put this little bit from Calvin out there. A smidge of context is needed first.
Many of the proponents of the “two kingdoms” theology in the Reformed world read Calvin as teaching that the “spiritual kingdom” is the church, and the “temporal kingdom” is the rest of the outside world. This is incorrect and actually approximates the old Roman Catholic position. For Calvin, the spiritual kingdom is the invisible church, and the temporal kingdom is the entire external realm- visible church, state, and family. Here’s a short quote that gets right to the point. From Calvin’s commentary on 1 Cor. 11:1-16:
There is somewhat more of difficulty in what follows. Here the man is placed in an intermediate position between Christ and the woman, so that Christ is not the head of the woman. Yet the same Apostle teaches us elsewhere, (Galatians 3:28,) that in Christ there is neither male nor female. Why then does he make a distinction here, which in that passage he does away with? I answer, that the solution of this depends on the connection in which the passages occur. When he says that there is no difference between the man and the woman, he is treating of Christ’s spiritual kingdom, in which individual distinctions [“External qualities” -ed.] are not regarded, or made any account of; for it has nothing to do with the body, and has nothing to do with the outward relationships of mankind, but has to do solely with the mind — on which account he declares that there is no difference, even between bond and free. In the meantime, however, he does not disturb civil order or honorary distinctions, which cannot be dispensed with in ordinary life. Here, on the other hand, he reasons respecting outward propriety and decorum — which is a part of ecclesiastical polity. Hence, as regards spiritual connection in the sight of God, and inwardly in the conscience, Christ is the head of the man and of the woman without any distinction, because, as to that, there is no regard paid to male or female; but as regards external arrangement and political decorum, the man follows Christ and the woman the man, so that they are not upon the same footing, but, on the contrary, this inequality exists.
Notice here that Calvin says Christ’s kingdom does not concern the body or any external relations. It is wholly inward and has to do with conscience. Thus there is total equality and immediate relationship between Christ and all believers in the spiritual kingdom.
The temporal kingdom is different. It has to do with the body and all external conditions. It still has mediation and hierarchy. This is how Calvin defends against forms of egalitarianism which would stem from certain Pauline texts. All of the “spiritual kingdom” truths have to do with the life of the soul. Notice also that Calvin says “ecclesiastical polity” is a part of the external realm, civil order, and ordinary life.
Much follows from this, but I’ll have to leave that for another time.
Wedgewords 
This seems to be a good example of Calvin’s Protestant scholasticism versus Roman Catholic scholasticism! The Two Cities or
Two Kingdoms of Saint Augustine may have been different than this. Saint Augustine says that the two kingdoms are both internal, spiritual dispositions of the heart towards God and His good creation both visible and invisible. These two antithetical dispositions are at war with each other both in the visible and in the invisible world. Saint Augustine uses the literary device of antimetabole or chiasmus to describe these two antithetical dispositions of the heart towards God’s One Kingdom. “Fecerunt itaque ciuitates duas amores duo, terrenam scilicet amor sui usque ad contemptum Dei, caelestem uero amor Dei usque ad contemptum sui. “Likewise, two cities have been formed by two loves, the worldly by the love of self, even to the contempt of God, the heavenly by the love of God, even to the contempt of self.” Augustine, City of God, XIV.28 (AcBdAdBc) (parallelism with love & contempt, chiasmus with
self and God).”
http://en.wikipedia.org/wiki/Chiasmus