Isn't it 1% per county conquest? I hope I'm wrong about that, but I'm pretty sure it's 1%. Building temple holdings should give you another 1% per temple, and putting down religious rebellions should net you 1% each. According to ckiiwiki, you can get 3% per ruler conversion, which I assume would have to be done with your Diviner (religious advisor). Seems pretty unreliable, though, especially as an unreformed pagan. I've got a Buddhist vassal I'll try to convert tonight.
There's one desperate measure that one could try...Fabricate a claim on Baghdad and/or Heliopolis, hope for a rebellion, try to ninja the the county, and immediately reform if successful. Super gamey though, if it's even possible.
There's one desperate measure that one could try...Fabricate a claim on Baghdad and/or Heliopolis, hope for a rebellion, try to ninja the the county, and immediately reform if successful. Super gamey though, if it's even possible.