Widely acknowledged by whom exactly?
Certainly not by anyone that understands the origins of Western Law.
We base our system of laws on English Common Law, a system of laws introduced into England by the Saxons on their settlement of England, which was about the middle of the fifth century, but Christianity was not introduced until the seventh century, thus we see a two hundred year gap between the adoption of the system of laws which led to the Magna Carta, which IS the widely accepted foundation of all Western Law, and the introduction of Christianity in England.
It would have been quite difficult to base the laws of a nation on Commandments that were two centuries away from being pronounced on their soil.
You dispute the kind of foundational role asserted in the statement of Gargantua. Disingenuous word-parsing! No serious person disputes that the 10 commandments has some sort of foundational role. The question is whether displaying the 10 c's establishes a religion. It doesn't.