the entire issue is obviously deep and requires much study... ignoring the vitality, though, of the grafting of Christianity is kneejerky imo... but I am still learning:

"Thus, at the arrival of the Anglo-Saxon tribes in Britain, the Scriptures and its ideals had adopted and cradled their Volkriht, which England later called the common law.552 Britain, being insular, allowed the Scripture's and the common law's early incubation among the inhabitants and later free development in open rivalry with the canon and civil laws, according to the measure of fair play, namely, due process. In Britain, the playing field was more level than on the continent. The native genius of the common law is its adversarial character; demanding conflict, it draws life and strength from adversity. In a word, battle by trial according to fair play over real questions of life and property, is the life of the common law. In Britain, the civil law's attempts at subversion of Scripture and assaults upon the common law, therefore, enlivened its soul and enhanced its effect; focusing attention on its fundamentals, it tempered them, refined its identity, and spread its authority.  

The Anglo-Saxon, long before migrating to Britain, had concluded aright that neither he nor any other mere mortal or combination thereof could be, by any stretch of sense, the fountain of law; on this truth he had set his deepest religious conviction and his practice of law and government.553 The Christian Scriptures offered the same conclusion, but with the added benefit, unavailable anywhere else, of relief from the power of sin and guilt—an offer irresistible to the one called of God.  

Modern common-law forms and principles are traceable to the early Germanic folk law. Beyond that, human reception of the common-law tradition grows dim in the fog of antiquity. Of these tribes, the common law has descended direct from the traditions of law and government of the Anglo-Saxon and Danish tribes554 that migrated to England during the fourth through the ninth centuries. Though the law and government of the Celtic tribes in Britain before the Anglo-Saxon and Danish migration had been practically indistinguishable, the Roman occupation had compromised the controlling features of the Celt's law and government.  

Beside the Germanic tribes, other ancient peoples and nations had developed traditions of law and government similar to the Volkriht. None, of these, however, survived, as did the early law and government tradition of the ancient Teutonic tribes of the northwest of Europe, which were akin even in their particulars, all bearing a striking likeness. Upon the Anglo-Saxons' arrival in Britain, their ideals of law and government merged with the Celts', overcoming the Roman influence for at least the next two centuries. During this period, the British Church flourished, resting for its authority on Scripture and forming its government independent of Rome's law and her imperial church. Then, the arrival of the Danes quickened and strengthened the common law's recognition of the sanctity of personal relationships and of individual property ownership."

552 At the time Christianity adopted the common law, the Anglo-Saxons called its principles, taken together, their Volkriht (folk law).  

553 See generally § 3.2.1 (discussing the pagan Anglo-Saxon understanding of fate and judgment). 

554 See generally § 3.4 of this book (discussing the Danish resurgence of the folk law among the Anglo-Saxons). From the Latin, tribe signifies a “sprouting up” or “growth.” Tribe, therefore, is a good translation of the old Norse root, stamms (English, “stems”): “from a common root.” A tribe consists of those descended from a well-known common ancestor, as, for example, the tribe of (descendants stemming from) Judah. See, e.g., Isaiah 11:10, Romans 15:12.