Following on from the first book, The Winter King, Arthur has achieved temporary peace across the south of England via shrewd diplomacy and on occasions, war. Cornwell's trilogy portrays Arthur as an oath-bound Lord sworn to protect the kingdom of the infant King Mordred against the Saxons as the country itself is torn apart by warring Christians and pagans. Arthur is a principled leader who remains true to his oaths even as they overpower him and conflict with each other.
As with the first novel, the story is told retrospectively by the main protagonist Derfel, a former warrior and now monk loyal to Arthur. By telling the story in such a way, Cornwell maintains the suspense as the reader is aware of Derfel's present situation (writing the story in a monastery) but unclear how he ends up there from the story he is telling which is a world apart.
The book has an underlying theme of atheism common to modern times as Cornwell narrates the escalating threat to peace of the warring Christians and pagans and Arthur's struggle, despite all his best diplomatic efforts, to bring harmony to the rival religions.
I am largely unfamiliar with the story of Arthur and his knights of Camelot, and I enjoyed Cornwell's attempt to retell the story without all the usual romantic legends, however, in comparison with the first book, Enemy of God does feature more magical goings on as Merlin ropes Derfel into his quest to find the Treasures of Britain. The ending is particularly exciting as Arthur's friend Lancelot shows his true colours and places the story's heroes in danger while setting the scene for the final instalment of the trilogy.
A good mixture of history, legends, magic and religion.