What is the importance of spirituality in the novel, The Harrowing of Gwynedd?

Deryni protagonists delve into ancient mystical practices out of necessity. As a result, they see glimpses of a more profound unity among Deryni magic, Christian sacraments, and the Power beyond. The horizons this suggests are only hinted at, but they include the ultimately benign nature of the universe, and a possible new spiritual synthesis. While the details of the emerging synthesis are no doubt based in the author's own vision, its general shape may reflect a growing openness to new symbolism and ritual in many mainline churches.