We’ll have to trade Peter CS to get it, which puts him into Bureau and Friendly.
Unfortunately, we need Friendly before we can get Philo.
We would rather not change religions until after the GAge, so once we get banking, it would go:
Start GAge, switch to confu for +1 diplo, trade for philo, switch to Merc+Philo
Therefore, we can't build up more than +1 shared religion
But, we could get +2 or +3 shared civic.
So we'd trade something like Math+Priesthood+Medi? for IW + poly, CoL for Alpha, CS for Monotheism? no, probably Monarchy.
Point being: we give up CS pretty early.