Religions/home city

[Asmodeous]

I have found the holy city of any religion you found ends up in the last city you built before the tech was finished researching.

I've honestly never seen it do anything else.

Me.

[Blake]

The holy city algorithm goes like this:

0) It prefers to not found in the capital.
1) It prefers cities with fewer religions.
2) It prefers higher populations.

That's in basic order of strength.
Things which don't matter:
A) When the city was founded.
B) Whether the city is already holy, the religion* just counts as a religion for #2.

Unless you're deliberately engineering things, a newly founded city will likely have fewer religions than established cities, but you can engineer things by having missionaries waiting. In a number of games and SG's I've engineered multiple-holy cities later in the game, like getting Islam in an existing holy city, it just requires putting more religions in every other city and if possible raising the population of the target city. In BTS I've seen the AI get Islam in an existing holy city. It doesn't do it deliberately, but because the CV AI is very good at filling every city with religions, Islam will tend to go to a larger city - which will often be one of the most mature cities.

[wodan11]

I've found that Blake's (1) criteria is the telling point.

Look around your empire, and you'll find that you can pretty easily narrow down the possible cities that the new religion will go to. Either you have a brand new city with no religion (and the new one goes there automatically), or else you have 1-2 cities with only one religion.

The latter happens more often than you might think... usually you have your State religion, and you make an effort to spread it to all your cities (to get Organized Religion benefits or whatever). However, when you found a new city it will soon get a religion from natural spreading. If it's your religion, then you're done. If it's not, then you spread yours to it.

Thus: you pretty much always have 1-2 cities with no religion, or else 1-2 cities with only 1 religion. And that's where the new religion will go in either case.

Bottom line: if you keep a key missionary or two you can control where the new religion is founded. This can be very handy.

Wodan

[Virdrago]

Not really knowing the algorithms, the reasons I mentioned my points were
a) my second city usually is my largest (or close to), and
b) I like to use missionaries when I can, so I don't have my fur outpost on the tundra island founding Christianity.

I have had my second city founding up to four religions before, and it usually founds anything besides Buddhism, thus my positing.

Thanks for enlightening me.

[VoiceOfUnreason]

Originally posted by Blake

Things which don't matter:
A) When the city was founded.

That's not quite right.

The tie breaker (after all of the other considerations, including a random number just to keep things from being too predictable) is city order, with earlier cities in the list getting priority over later. You can see what the city order is by looking at the domestic adviser.

That list will look suspiciously like founding order, until you realize that the cities you captured appear based on when you captured them, not based on when they were originally founded, and so on.

In short, the turn on which a city was founded matters not at all (provided that it was founded prior to the discovery of the religion, of course). The relative ordering of the founding of the cities matters some (in the weird tie breaker edge case), but isn't quite the whole story.