[Kristoffer O]

Initially we didn't intend for good and evil, holy and unholy to be in the game. Evil is in the eye of the beholder.

Unholy was added as an ad hoc solution to the fact that holy priests were more or less useless to undead priests of Ermor (dom1). At that time bless effects etc was handled a bit differently and most of ermors troops didn't have morale. Preaching was also something we imagined the undead didn't do. Therefore unholy priests were added.

Currently you can consider unholy those priestly powers that are influenced by the underworld and the unliving. Unholy has always felt a bit ad hoc. Especially when broken empire Ermor got unholy priests. They were made to be able to preach and reanimate.

Unholy is getting a rework in DOM3. Undead priests have 'unholy' powers of reanimation, but the unholy tag is removed. All priests are priests.