The followers of fire worship the elemental force of Fire.
Fire is a True neutral force.
Priests are usually Clerics; many are multiclass Cleric/Wizard/Sorceror/DragonDisciple.
Followers can be of any alignment,
Cleric domains: Fire, Animal, Death, Destruction, Good, Knowledge, Magic, Plant, Protection, Strength, Travel, Trickery, War, Sun
Forbidden Domain: Water