Ideologies in the Mists
San Francisco started out as one of many Catholic missions established in California by Spanish priests. The priests and the natives of the land flourished together with the father, the son and the holy ghost for many generations. Then in 1834, the Mexican government smashed the mission system in an attempt to secularize the country. Priests were persecuted and the natives scattered like Jews in the desert.
The fogs of San Francisco Bay were mirrored by the hordes of people flowing onto the land in search of gold. People of all languages, religions and nationalities confused the religious landscape, made it difficult for the Catholics to regain the control they had lost. But they kept their presence in California, even when they had to hide.
The same sort of thing is happening in The Mists of Avalon. The Christians are taking over the land, persecuting the Druids, who must create a shroud of mist to hide the practice of their faith. Their actions are defensive, grasping in the fog to maintain control, to keep from losing their faith, when finally they realize that the Madonna is just another incarnation of the goddess, and She is eternal.