Religious event
The High Priestess' successor, a young man named Adam Hathal, receives a visitation from a Dark Luminary. He falls into deception as a result of this and begins spreading that deception to the rest of the Order.
Shortly before the passing of the High Priestess, successor Adam Hathal is meditating in his private quarters, when he is visited by a Luminary. The Luminary offers a commission of making a new edition of the Holy Scrolls, which will bring more unbelievers into the Order. In his excitement at the visitation and the being's message, Adam Hathal accepts the Luminary's commission, neglecting to first test it to see if it's really a demon in disguise. As a result he is deceived and, once established as High Priest, releases his heretical edition of the Holy Scrolls for public use in temples.