It is worth remembering that Calvin’s view of government was aristocratic. The king’s power was not to be absolute, but he is to govern together with his nobles. Calvin’s treatment of civil government is in Book IV of the Institutes, the last chapter (20). At the beginning of Book IV Calvin explicitly links to his earlier teaching on the two kingdoms.
I’ve heard it said that John Calvin was not in favor of rebellion against the government, and that it was John Locke to whom would-be rebels looked to justify Christian rebellion, as we might call it. For a recent example of this view see here. But I think the matter is a bit more complicated than that, and that a case can be made for Calvin leaving open, in fact if not in intention, the legitimacy of rebellion as a last resort against civil injustice.
It is worth remembering that Calvin’s view of government was aristocratic. The king’s power was not to be absolute, but he is to govern together with his nobles. Calvin’s treatment of civil government is in Book IV of the Institutes, the last chapter (20). At the beginning of Book IV Calvin explicitly links to his earlier teaching on the two kingdoms. (Book III.19)
The former [kingdom], in some measure, begins the heavenly kingdom in us, even now upon earth, and in this mortal and evanescent life commences immortal and incorruptible blessedness, while to the latter [kingdom] it is assigned, as long as we live among men to foster and maintain the external worship of God, to defend sound doctrine and the condition of the church, to adapt our conduct to human society, to form our manners to civil justice, to conciliate us to each other, to cherish common peace and tranquility. (IV.2)
You might ask why if Calvin holds to the two-kingdom doctrine, the Institutes should contain any instruction in political matters. The answer is because he believes that the NT teaches that government is warranted and put in place by God. As Paul says, the powers that be are ordained of God. Christians need to be reminded of this, he thinks, just as they need to know what the limits are to the powers of government.
It is widely believed even amongst Reformed people that Calvin was mistaken in including the part that I have quoted among the duties of the civil magistrate. The state should not try to protect the profession of the faith (as Calvin thought), but (instead) provide a public square in which any religion and none may or may not peaceably flourish. Calvin was a stranger to freedom of worship and toleration, as he was to a universal electoral franchise. He interpreted Paul’s words to Timothy “that we may lead a quiet and peaceable life in all godliness and honesty” rather more strongly than most Christians today would interpret it. But nothing (I think) turns on this in what follows.
The Forms of Government
In Chapter 20 of Book IV of the Institutes, Calvin also says something about forms of government in general.
And if you compare the different states with each other, without regard to circumstances, it is not easy to determine which of these has the advantage in point of utility, so equal are the terms in which they meet. Monarchy is prone to tyranny. In an aristocracy, again, the tendency us not less to the faction of the few, while in popular ascendency there is the strongest tendency to sedition. When these three forms of government, of which philosophers treat, are considered in themselves, I, for my part, am far from denying that the form which greatly surpasses the others is aristocracy, either pure or modified by popular government, not indeed in itself, but because it very rarely happens that kings so rule themselves as never to dissent from want is just or right, or are possessed of so much acuteness and prudence always to see correctly. Owing therefore to the vices or defects of men, it is safer or more tolerable when several bear rule.