During last stream devs said - I am not sure if this info appeared before - that
a) Historically 'personal unions' were almost exclusive to European continent thus now they will be available only for Christians
b) However other religion groups will have enabled Royal Marriages between each other (such as Sunni - Sikh) as - opposite to PU - it has been not - so - rare outside of Europe.
Personally I love it as pre AOW personal unions were already almost always happening in Europe while inter - religious marriages are awesome option. Also not sure if this will be feature exclusive for ROTW but if yes: it will be yet another thing differentiating European and non - European gameplay.
a) Historically 'personal unions' were almost exclusive to European continent thus now they will be available only for Christians
b) However other religion groups will have enabled Royal Marriages between each other (such as Sunni - Sikh) as - opposite to PU - it has been not - so - rare outside of Europe.
Personally I love it as pre AOW personal unions were already almost always happening in Europe while inter - religious marriages are awesome option. Also not sure if this will be feature exclusive for ROTW but if yes: it will be yet another thing differentiating European and non - European gameplay.