True authority is inseparable from the public profession of Christianity. All men must face God’s judgment, and therefore every area of man’s life must be governed by God. This means that true religion is necessary, and this, [Pope] Leo [XIII] said, Christ “committed to His Church to protect and to propagate.”
God has established two powers, the ecclesiastical and the civil. Each must have a regard for the nature and power of the other. Religion is a public concern and cannot be left to private judgment any more than civil government can.
The attempt of the state to reduce the church to the status of ordinary private association is an act of arrogance. “To wish the Church to be subject to the civil power in the exercise of her duty is a great folly and a sheer injustice.” The people are not the source of authority; “the origin of public power is to be sought for in God Himself, and not in the multitude.”
Rushdoony, R.J. (1986). Christianity and the State. Ross House Books, Vallecito, p. 172