In fact thats easy... if you know how to mod

I will give you advice here but I will not solve the problem for you... do not even ask
EDB:
add to some buildings capability ( example castle/city walls )
trade_base_income_bonus 1 and blabla
now here I forgot the exact stuff to write... instead of blabla you need the religios condition used in SS or TATW ( most mods ) where most units can be build only if there is a percantage of some religion reached... simply copy and paste that and change the number + the religion name!
create some jewish buildings...
campaign script:
monitor these buildings and if they exist
set the jewish religion to 1 2 or 3 %! Do not
increase as this would affect the religion in every turn!
Now thats all
You can add more then one income bonus... one activates at 5% another at 10%...
Btw : Every question you might have about what I wrote is answered here =>
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