Many Reformed writers before and into the twentieth century viewed broader cultural activity, particularly political and legal life, through a doctrine of the two kingdoms. This doctrine asserts that God’s rule of the world is twofold, a preservative and temporary reign over civil life and a redemptive reign over his church that will be consummated in the heavenly Jerusalem. According to this paradigm, Christians should indeed be actively and righteously involved in the many arenas of human culture, but, in their political and legal activity, they serve as agents of God’s general and providential rule of this present world—not as agents of his redemptive work in advancing the eschatological kingdom of Christ. Specifically, I focus on the postdiluvian covenant with Noah in Genesis 8:20–9:17. I argue that the Noahic covenant provides substantive theological foundation for believers seeking to build a political or legal theory consistent with Christian truth, offering crucial rudiments from which Christian legal and political theorists can build using their own prudence and expertise.