Princesses and Priests have already been dealt with, same for the Pope. I was unsure if I should keep one or two, to represent Josephine de Beauharnais and Louise of Mecklenburg but I'll probably discard the idea.
As for religion, it will be used as political orientation when the French or the Coalition forces conquest settlements.
Namely:
Bonapartist
Reactionary
Conservative
For the Russians I was thinking about giving them a unit in battle with the ability to chant that carries a big icon of the virgin Mary across the lines before battle but this is just a concept for now. We will see.