The Heretics' Power by Ken Baumbach

In this Epic fantasy, war looms over Reldaria. A new religion divides the kingdom as the Ancient Ones fear the Heretics' Power...Wuldarad, a priest of the Ancient Ones, meets Palidor, a master of a new religion, the Sons of Light, and trains with him. He brings newfound knowledge back to Sarkuth, the high priest of the Ancient Ones, only to be attacked by his former mentor and friend. Wuldarad escapes and the following of the new religion grows.As the Sons of Light grow in power, Sarkuth, growing more fearful and angry, brings the kingdom to the brink of civil war!