In one campaign that I would like to run, the continent on which the campaign takes place is ruled by a theocracy devoted to the Four. Detect spells and effects are more complicated in this campaign, and there is no alignment (except for outsiders).
Clerics cast spells differently. Clerics cast the same number of spells per day, but may only cast spells from the domains that they know, plus a number of 0th-level spells equal to their wisdom score plus their caster level. Clerics start out with two domains, as usual, and gain access to spells from additional domains by taking initiate feats (these feats do not grant the domain ability) and at 10th and 20th level.
At tenth level and twentieth level, a cleric chooses a domain which he does not have access to; he can now cast the spells of that domain. After making this selection, the cleric chooses a domain he can cast spells from and gains that domain’s power. The domain gained at 10th level must be one of the cleric’s god’s domains.
Clerics of the Four choose one god as their primary; both of their first level domains, and the domain spells they gain at 10th level must be domains of this god.
Clerics can work with their DMs to create spell domains for their god – domains with no domain ability with thematically linked spells appropriate to the character’s god.
If a cleric would gain access to the spells of another of his gods domains, but already has spellcasting access to all of that god’s domains, he may choose a domain of another god in his god’s pantheon. If he already has spellcasting access to all of those, he should consult with the DM to find another domain.
At first level, clerics do not automatically gain the ability to turn undead, but instead choose any channeling feat which they qualify for.
Clerics have an aura of their gods, not Good