WHO : The clerics and same deity characters .
WHAT: Clerical zone buffs are improved. Bless and prayer give +2 to rolls instead of +1 to the faithful of the same deity, for example.
WHY: Gives a mechanical incentive to have several characters share the same faith. The same way nonhumans get a bonus from racial domain turn undead abilities, but have it act as a faith unifier instead of race.
As a cleric player myself I would not want to see this implemented.
Call me a negative nancy but Bless is already good enough for a 1st circle spell and there should not be a mechanic incentive for characters to follow the same deity but a RP incentive instead.