After playing Civ 4 for a while I am realizing just how incredibly powerful it is to have multiple religions in your cities well before the free religion civic. For every religion in your city you may build one temple and one monestary. Each temple increases happiness (as well as culture) and each monestary increasing scientific output by 10% from that city (as well as more culture). And these bonuses stack! So if you have Buddhism and Taoism in one city, you can build two temples and two monestaries. Double the happiness,double the culture, double the scientific output! Then of course if you actually found multiple religions in your cities you can build multiple shrines, spread multiple religions and thus collect alot more gold! The gold you collect through shrines is almost on the level of ridicule. I usually spend a little time building missionaries in every city to spread my religion throughout the world. I end up making so much money I could care less about how many cities I build and how many units I build. And this is with just ONE religion. If I found more than one religion I can multiply this bonus even more. There seems to be no penatlies to having multiple religions to force you to make a decision. The only drawback to spreading multiple religions to other lands is that the foreign nation may convert to something other than your state religion and thus start to dislike you I think one thing that could be changed is the gold collection form shrines.. it's just too much! And every city no matter how big or small gives you the same amount. Maybe make it so the larger cities give you more gold than smaller ones?