In that case, I'll take:
Interfaith Dialogue: Gain Science when a Missionary spreads this religion to cities of other religions
Holy Order: Missionaries and Inquisitors cost 30% less Faith
and one of:
Tithe: +1 Gold for every 4 followers of this religion
World Church: +1 Culture for every 5 followers of this religion in other civilizations
depending on what you need.
then I'd add (still get two followers)
Choral Music: Temples provide +2 Culture in Cities with 5 followers
Religious Center: Temples provide +2 Happiness in cities with 5 followers
Since you're going to have them anyways. Likely Piety would also be a good choice (even if not going cultural) and boom - spam cheap missionaries to get both beakers and gold/culture (depending on what you picked).
Neither Tithe nor World Church require you to flip the city to your religion, so Interfaith Dialogue can be used against any city that hasn't flipped. If the AI is good at using missionaries/inquisitors, they'll constantly give you more 'target' population to flip.
See how it would work, though? The bonuses gained just from that would be great, even though if it was a UA, it would not be good by itself, it'd be great together in a full religion setup. The Byzantines will have a leg up as long as they follow through with religion.