I've been playing Civ4 for a few days now, and in my current game, I found something which should be addressed, hopefully by Firaxis. It wasn't until the 1700s that my Arab civ crossed the ocean and found an AI civ which had been all alone on its own continent. During the centuries prior, the other 4 civs and I had discovered all the techs for the various religions in the game. So that lonely civ had never developed any sort of religion on its own, and that's not correct. It's pretty safe to say from any examination of human culture that religions have developed in every society. I suggest that the engine be tweaked in some fashion, either with some sort of default paganism/animism or that if in the ancient age civs fail to discover the techs, or don't have contact with other civs to have religions come into the culture, that some sort of paganism/animism be granted to that civillization.