I have a slightly different approach to suggest and would like to discuss it.
It is based on Samuel Huntingtons theory of
"Clash of Civilizations". Basically this theory says that in post-Cold War era the main source of conflicts will be the cultural identities of the peoples.
Thus Huntington defines several "Civilizations" who will evoke conflicts with each other. For our game I would use the following "Civilizations" (i.e. Civilizations in terms of Huntington not of Civ IV):
Western (Western Europe, North America, Australia...)
Orthodox (Russia, Greece, Ex-USSR states...)
Latin American
Muslim
Hindu
African (Sub-Saharan Africa)
Sinic (China, Vietnam, Korea...)
Buddhist (Most of East Asian countries)
Jewish (Israel)
Huntington was most critisised for the implication that there could actually be "alliances" of states with the same culture against an alliance of states of an other culture. This seems unrealistic because it would unite states of totally different international interests. But this is exactly the point what makes this theory interesting as a substitute for religions in our game.
This
"Cultural Orientation" would, like religions do in vanilla, link civs with the same Cultural Orientation but at the same time would leave them their independence as autonomous civs.
Another nice feature of this system is that you could actually symbolise different ethnics in melting pot cities like NY or London and actual conflicts with an ethnic dimension like in Sudan, Yugoslavia or Israel could be simulated.
I'm not sure how complicated it is to have more "religions" than in Vanilla but one could narrow the list down to 5 or 6 Cultural Orientations. But more is better.
