I just played a game where Judaism became dominant in my area of the world, despite not having any missionaries. A faster spread rate is really quite a significant boost. However, the porblem with the playtest game was that while Judaism spread just fine, it was ll conglomerated in one place (ie a big blob o' religion). This could have happened historically -- but it didn't. I'd love to have a way of simulating the diaspora. Ironically, when it comes to game mechanics Christianity (cheap missionaries but little natural spread) looks more like a diaspora faith, with a small core and many outposts around the world, than does Judaism (no missionaries but a compensating higher rate of natural spread).
Any ideas on this? I'm not sure if this is a problem or not, and I'm not sure how to fix it if it is