Moorindal, the God of Shadow
Evil is an integral part in any religion. Moorindal, the God of Shadow, is represented in one way or another in all of Arcanum's pagan religions. Moorindal is the bastard son of the moon and Helion, the God of Light. Patricide is always associated with Moorindal, as legend tells that once Helion ruled over both the day and the night, but that Moorindal killed him so that the night could be his and his mother's. So the night became the kingdom of Moorindal, as did the winter months.
There were many secret cults and religions that worshipped Moorindal, but we know little about their practices and perhaps that is for the best. We do know that they used the black diamonds from the Bangellian Deeps as offerings to their dark god. It represented loss of innocence, the triumph of the shadow.