Not so in Christianity. The reason is spelled out in the church father Augustine’s great work The City of God. Augustine argued that during our time here on earth, the Christian inhabits two realms, the earthly city and the heavenly city. (Only at the end of time will God integrate these two into a single majestic kingdom ruled by Him.) To each of these realms the Christian citizen has duties, but they are not the same duties. Yes, the Christian gives his ultimate devotion to the heavenly city. But some remarkable conclusions follow from this primary allegiance. It means that the earthly city need not concern itself with the question of man’s final or ultimate destiny. It also implies that the claims of the earthly city are limited, that there is a sanctuary of conscience inside every person that is protected from political control, and that kings and emperors, howevergrand, cannot usurp authority that rightly belongs only to-God.
Here we see, in its embryo, the idea of limited government. This idea derives from the Christian notion that the ruler’s realm is circumscribed and there are limits beyond which he simply must not go. Those limits were originally set by the church competing with the state and establishing its own realm of authority. Let’s remember that the church was not simply a spiritual institution—holding services and administering sacraments—but was also a temporal power, possessing huge properties and in some cases even commanding armies. For centuries the kings and the church fought over how to draw the legitimate dividing line between the two spheres, but both sides agreed that there was a dividing line. The kings have now been replaced by democratic government, but the Christian idea persists that there are some things even elected governments cannot control.
