I think I'll follow a similar approach. Each religion will have its own unique "cleric" class variant, ranging from the semi-druid Priestess of Meya Ennah (the Celiran Mother Goddess), through the combative Dwarven cleric of the Smith-God (similar to the PHB Cleric though more Earth/Metal/Smithing/Technology oriented) to the various Shamans and Adepts of the more animistic faithes. I'm even considering creating a PC-class variant of the NPC Adept - a Witch (or Witch Doctor). IMC, some Humans are shamanic, some worship the Dwarven Smith-God, some worship Meya Ennah, and some follow a politheistic pantheon. However, priests of that pantheon would probably be closer to Wizards in terms of combat ability - they'll have extensive (far beyond the PHB cleric) Divine spells at their disposal, but they won't be front-line fighters (1D4 hit dice, bad saving throws, bad BAB).el-remmen said:Each god (or set of gods) has its own variant priest class with its own abilities, spell list, powers, and limitations.
IMC I use a very loose alignment system - low level mortals do not have clear alignments, but outsiders and gods do, and so do mortals who are closely bound with such beings. A cleric has to follow the alignment of his diety, or, in the case of Meya Ennah's priestesses, the alignment of the aspect of that goddess which they follow. Shamans also develop an alignment which becomes clearer as they gain levels, and it effects the spirits they interact with.el-remmen said:Alignment: Typically priests must be the same alignment as their god, however, some priesthoods are allowed more leeway in their alignment. If at any time a priest's alignment changes to one not allowed to the priesthood, he or she becomes an ex-priest.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.