Indeed I did, but I didn't switch religion, it was simply the first to appear in one of my cities. Buddhism has STILL not spread to my cities. I'm not sure how this works, but it is possible that the steadfast refusal for open borders from the two original Buddhists (Japan and Aztecs) probably had something to do with it.
As far as I know, I can't switch until at least one city has it, right? When the Aztec war started, Russia was also Christian, so it was two and two and it didn't seem too bad to have it that way. Once I was in war mode, I really wanted the extra experience points for my units, so even if I could have swapped, I don't think I would have.
At this point, as I mentioned, I was hoping to convert Peter back, but if I get a Buddhist city, I will take your advice and change over myself. I doubt it will keep the Aztecs from another attack, but it should open up some opportunities with the other two (for now.)
As for diplomacy, I've been researching things that are generally useful for war making, and even if technology trading was possible, I'm pretty sure I don't want to give any of these other civs construction, iron working, and anything else on the path towards civil service. It's a real challenge here. I'm even thinking about making a quick line to get me a caravel and seek out the rest of the civs.
You are right that open borders increase the speed at which religions spread. Religions can also only spread naturally to cities that don't have a religion yet, so if you've spread Christianity to all of your cities, then you can forget about a natural spread of Buddhism to one of your cities.
I always try to get good relations with civilizations at the start of the game. It's often very hard to change bad relations to good relations. For instance, once you have bad relations, you usually can't get open borders treaties and thus you can't get missionaries inside of their cities and thus you can't convert them. So you're stuck with different religions and that means bad relations. (You could use a spy to force a religion change upon them if they have a single christian city, but they're likely to convert back.)
At the very first moment that you meet a civilization, it's usually not that hard to get an open borders treaty except when you already have different religions or if you're a friend of their worst enemy (have a treaty with their worst enemy). When you open your borders to other civilizations, you will get a trade bonus inside your cities and over some time a diplomacy bonus will appear which will grow to +2 over time. These improved relations allow you to trade technologies and resources with them which will be good for your empire and further improve relations. If you have a city that has a foreign trade route with one of their cities with a religion, then this religion will quickly jump to your city which will allow you to get the same religion which gives a huge diplomatic bonus.
However, if you keep borders closed at the start of the game, then the other civilizations will open border among each other and become friends. They will trade technologies and resources and their religions will spread to each others lands. If you also refuse a few of their demands, then you will quickly be the most hated civilization on the continent and wars will erupt against you.
So a few small diplomatic decisions at the very start of the game can have a big influence on the remainder of the game. I wouldn't be surprised if you could replay the game and get excellent relations with your neighbours if that was your primary goal in that game. Of course, it often isn't the primary goal in the game and thus relations may suffer because you try to reach some other goal.
It will sometimes cost you something to get good relations. If someone demands an important technology from you at the very start of the game shortly after contact has been made, then it is very tempting to send them away with an insult. However, if you take into account all of the repercussions of this denial, you might find out that it is cheaper to give them a technology than to be the most hated civilization on the continent. It's very hard to oversee the consequences of some of the diplomatic decisions that you make at the start of the game. It's not a purely deterministic result; some of the effects are slightly random as there are some random factors in the AI decision making in order to make their decisions less predictable. There are also lots of uncertainties at the start of the game. Often you don't know all of the civilizations on your continent and you don't know which religions have spread in their cities. You don't know how the relations will form between them. If they start hating each other, then it's better to choose a side than to try to be friends with all of them. With some practise, you will be able to control your relations with other civilizations and become the puppet master of the world.
Ahhh, I finally find a good newbie topic to ask all my embarrassing questions.
I recently got Beyond the Sword and was really excited to play my first map. I got a huge map, continents, 16 nations, Prince difficulty (I believe, it is an upper middle skill), quick speed, and started in the future era (I have not found a way to edit the units, upgrades, and tech tree to my liking enough to play through from Ancient era). However, to my great dismay, I found that settlers cost a whopping 322 shields to make, more than some national wonders. This shocks me because, after playing on multiple maps with multiple factions in multiple types of maps, multiple number of players, and multiple tech eras, I discover that the price for settlers ranges from 64 to 330 shields and no matter what I do, I cannot figure what is up. This is on a completely unaltered set and I even went in and tried to lower the cost in the XTL files and cannot get any reaction. I saved my scenario and over multiple times on two days, have gotten a price range from 300, 303, 312, and 322 shields and it stays constant during the game, not varying through from turn to turn. I initially thought it was due to some settings I had and replicated these settings and got a different cost. I then thought it was due to number of cities (they give you three settlers) and I looked, that is not it because the price stays the same as I plant those cities.
I am completely at a loss as to what to do. I played about 50 turns and nobody else has built a city (checked World Builder). I would consider just going with it, but I am concerned that the incredibly high price would mess up the AI's strategy and make the game too easy for me. What on earth is causing this and how do I fix it? I did not have this problem on the original Civ IV when I played the exact same style of map and settings. Is this a bug or am I just missing a factor?
I don't have any experience with starting in an advanced era of development. Maybe this will increase the cost of settlers. I do know that the cost of everything is strongly related to the game speed setting. If you start a game at marathon speed, then the units will cost double the normal value and the buildings and technologies triple the normal value. You also have triple the normal number of game turns in such a game, so it balances out (somewhat).
Maybe someone familiar with starting in an advanced era could help you better.
You didn't mod the game, did you? You could have inadvertently changed something.