Alignment as New vs Old Religion

After reading the "Obligatory Alignment Post" at The Society of Torch, Pole and Rope I thought I would try my own. I just finished watching the first two seasons of Merlin the tv series. In the show, set in a mythical version of Britan there have been many references to "the old religion". This set of beliefs is tied to the Druids and to nature its self more commonly known as the old ways. One can surmise that in the series (although its never specified) the new religion is a form of Christianity. The struggle between these two systems sets the backdrop of the series. By simply renaming the new religion as Law and the old one as Chaos you have a viable alignment system that players can relate to. The knights of Camelot are the paragons of Law. The Druids are the diciples of Chaos. And the villagers are Nuetral. Based on how well this seems to work I'm considering switching my game to a medieval setting to incorporate this alignment system.