Are you threatening me, Master Jedi?

No, seriously that's perhaps the best reason I've been given so far. Much like Rome, where you could get excellent Scipii temples if you conquered them late. Getting the best temples from each faction allowed diversity in construction.

A pity your empire needs to be one religion. I'd love to see Orthodox cathedrals, Catholic cathedrals, and Islamic Mosques as well, all coexisting in the same town and offering a religious tolerance public order bonus to offset the religious penalty for not having a state religion.