Law is Inescapably Religious

"Law is in every culture is religious in origin. Because law governs man and society, because it establishes and declares the meaning of justice and righteousness, law is inescapably religious, in that it establishes in practical fashion the ultimate concerns of a culture. Accordingly, a fundamental and necessary premise in any and every study of law must be, first, a recognition of this religious nature of law.

Second, it must be recognized that in any culture the source of law is the god of that society. If law has its source in man's reason, then reason is the god of that society. If the source is an oligarchy, or in a court, senate, or ruler, then that source is the god of that system. Thus, in Greek culture law was essentially a religiously humanistic concept."
(Rushdoony, The Institutes of Biblical Law Vol. 1, p.4-5)