The famous Huguenot tract Vindiciae, Contra Tyrannos attempts to delineate the proper rules regulating the behaviour of rulers and subjects. At one point in its argument it discusses the matter of “the two kingdoms” (the term does not appear at this point in the document, but the idea is clearly recognizable):
Lest they should slip into such an appalling crime, it is above all necessary that princes should distinguish their jurisdiction from the divine; and with all the more scrupulousness because God and king both hold their right over the same ground and over the same thing — I mean over man.
Man is made up of body and soul: God formed the body and also infused the soul. Therefore He alone could use both of them with absolute right. But if He freely granted to kings that they might use the bodies and goods of their subjects only for the subjects’ preservation, they ought clearly to remember that the use was conceded, not the abuse. For above all, they have nothing which they may requisition [imperent] from the soul under the title of tribute, who themselves are bound to profess their own souls as liable to pay tribute to God. The king takes tributes or dues [census] from the body and from those things which are acquired or cultivated by the agency of the body; and God from the soul in particular, which actually exercises its functions through the body. To the former type of tribute belong renders in kind, money payments, and other dues both real and personal; … to the latter, sacrifices, congregations, and divine worship both private and public. These two tributes are so different and distinct that neither impedes the other; the fisc of God deprives Caesar’s fisc of nothing, but each one keeps its right. In short, anyone who confuses these mixes up heaven and earth and wants to reduce everything to primordial Chaos. 1