Because Judaism is probably the most influental and most important religion ever founded. Christianity and Islam are based on Judaism and I've always heard of "Shintoism" as Shinto-Buddhism. So if you're gonna have "Shintoism", you better have Protestants [N-America, Scandinavia, Germany, Benelux, Switzerland, Christian Africa], Catholic [S-Europe and S-America] and Orthodox [Russia, Greece and Ex-Soviet] or Shia [Iran] and Shia [Rest of Arabia]
All those have more modern followers than Judaism and "Shintoism", but I think that Taoism or Confucianism even has fewer followers than Judaism. I somewhere heard that Chinese Religions were about 3% of the world and Judaism about 1,5% so either Confucianism or Taoism has fewer followers. Where I live (Iceland) we study each religion, Judaism, Buddhism, Islam and Hinduism [of course Christianity] because in Iceland there is a free religion. But not Chinese religions, I don't know why.. Buddhism is probably about 5% of the country, even though Thai, Chinese, Phillipine, Vietnamese (and other Asians) people are only 2% of the country.
But that's out of subject.
In stead I think they should take either Taoism or Confucianism out of the game since Islam never really becomes a religion. It's founded in a town in the ice because there are no places left and spreads like nothing.
With no offence to Chinese religions
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And talking about religion. I think Meditation should require Polytheism because it's weird that Buddhism always comes in front of Hinduism, since Buddhism is an "offspring" of Hinduism.
Idea:! If I don't have any religion after founding Polytheism, I will make my own religion. If I was playing fx. Inca, the state religion would be Incan Polytheism, and other "civilized" religions would call me an even more heathen religious guy. That was reality. If a new religion spreads to my city (let's say Buddhism after it has been founded), there is a turn of anarchy, and then you can deside whether you want this as your state religion or not, and another turn of anarchy. That makes more sence than having NO RELIGION. Religion has followed the man since the first day he stepped foot on Earth.