How we cite our quotes: (Book.Chapter.Paragraph)
Quote #1
[…] the best building in Maridunum was the Christian nunnery near the palace on the river's bank. A few holy women lived there, calling themselves the Community of St. Peter, though most of the townspeople called the place Tyr Myrddin, from the old shrine of the god which had stood time out of mind under an oak not far from St. Peter's gate. (I.2.3)
Here's an early instance of newfangled Christianity butting up against ancient pagan beliefs in southern Wales. This is syncretism at its finest—that's when religions borrow from one another to accommodate different types of worship into one new version of practice. Merlin adds another level to the naming of the area, when the "Myrddin" of the old shrine also calls to mind the way he's taken over Galapas' cave (remember that his Welsh name is Myrddin).
Quote #2
Moravik had the biggest collection of charms and talismans of anyone in Maridunum, and I had never known her to pass a wayside shrine without paying her respects to whatever image inhabited it, but officially she was a Christian and when in trouble, a devout one. (I.2.48.26)
Moravik is Merlin's Breton nurse, and she's Christian. Well, sort of. Christianity is her baseline religion, but she also calls on the good luck charms of the old religions when the situation calls for something extra. Merlin's real point? Moravik is superstitious. And she's also, like Merlin, seeking powerful help wherever she can find it.
Quote #3
I had seen the soldiers' god, the Word, the Light, the Good Shepherd, the mediator between the one God and man. I had seen Mithras, who had come out of Asia a thousand years ago. He had been born in a cave at mid-winter, while shepherds watched and a star shone; he was born of earth and light, and sprang from the rock with a torch in his left hand and a knife in his right. He killed the bull to bring life and fertility to the earth with its shed blood, and then, after his last meal of bread and wine, he was called up to heaven. (II.6.21)
Stewart shows us how much overlap there is between the Roman legend of Mithras and the story of Jesus. This overlap suits both Merlin and Ambrosius just fine: they're not particular about names—they're only worried about power and light. In the end, they only care about the outcome. If Jesus is the way to power in Britain, then Jesus can be their new Mithras.