After andersw showed how Syncretism worked I really wanted to give it a try.
Essentially, a huge boost of Faith, Science, and Production to the Holy City for citizens in your empire following a different religion. Barring niche situations where say a neighbor has a better religion or someone like India will just passively shred your religion, or capturing a Syncretism holy city, you can very easily plan on having a strong Syncretism capital by founding a religion, picking this enhancement, and then allow the AI to convert your cities and pick up whatever religion(s) are nearby to spread.
To do this, I picked Mongolia, which loves to go warmongering at right about the perfect time (late Classic/Early Medieval, just after Annexing some CSs), and planned to found my religion specifically with Syncretism in mind. Pantheon is God of the Expanse, which provides a very reliable pantheon to found when paired with Ger and Authority border growth. Not only that but it lets me cover a wider area of my starting land without having to found too many cities so I can use more early happiness to Annex CSs. I then planned to use Theocratic Rule or Hero Worship, which are the only two Founders that make sense if I'm not spreading a religion, and Discipline and Scholarship will most likely be my two Follower beliefs, since this will only apply to my capital so buildings aren't helpful (plus I don't want extra pressure).
This plan worked perfectly, and at early Medieval with 6 cities most of my cities are converted to something else and my capital already has around +15 production from Syncretism. Alongside a nice pickup of Temple of Artemis I can pump out Skirmisher-type units insanely quickly. I also started on a continent which ended up founding 4 of 5 religions, one of them is Spain's, so I couldn't have spread my own religion anyway. Overall, it is feeling really good. I'll have to see how the midgame goes once I'm able to capture someone's religion (or multiple) and end up doing Mongolia's traditional "this continent is mine thanks for settling my cities for me" strategy.
I can't believe I hadn't thought of this strategy for warmongers before. Unless you're someone like Aztecs this seems like a really solid strategy, and AIs now make pretty good religions to steal anyway.
Spoiler For those who don't know what the Enhancer belief does, I've quoted andersw's findings: :
I finally figured out how syncretism works, I've seen others wondering about this so I thought I'd share my find.
From wiki
"
+1Faith,
Science, and
Production in Holy City for every 2 Followers of other Religion is owned Cities.
+5Culture when a Citizen is born in an owned City Following this Religion.
"
This contains a typo , the bold is should be "in owned cities".
The idea is I guess to go on a conquer spree and not spread this religion to other cities while growing your empire and getting a holy city with crazy faith/science/prod.
The holy city keeps this even if its not your majority religion, it also keeps the yields if you capture a holy city with syncretism, convert other citys but not this one and watch it explode in yields.
Here is a screenshot of a captured lategame holy city providing almost 200 each of the above mentioned yields from just syncretism.
View attachment 523333
Essentially, a huge boost of Faith, Science, and Production to the Holy City for citizens in your empire following a different religion. Barring niche situations where say a neighbor has a better religion or someone like India will just passively shred your religion, or capturing a Syncretism holy city, you can very easily plan on having a strong Syncretism capital by founding a religion, picking this enhancement, and then allow the AI to convert your cities and pick up whatever religion(s) are nearby to spread.
To do this, I picked Mongolia, which loves to go warmongering at right about the perfect time (late Classic/Early Medieval, just after Annexing some CSs), and planned to found my religion specifically with Syncretism in mind. Pantheon is God of the Expanse, which provides a very reliable pantheon to found when paired with Ger and Authority border growth. Not only that but it lets me cover a wider area of my starting land without having to found too many cities so I can use more early happiness to Annex CSs. I then planned to use Theocratic Rule or Hero Worship, which are the only two Founders that make sense if I'm not spreading a religion, and Discipline and Scholarship will most likely be my two Follower beliefs, since this will only apply to my capital so buildings aren't helpful (plus I don't want extra pressure).
This plan worked perfectly, and at early Medieval with 6 cities most of my cities are converted to something else and my capital already has around +15 production from Syncretism. Alongside a nice pickup of Temple of Artemis I can pump out Skirmisher-type units insanely quickly. I also started on a continent which ended up founding 4 of 5 religions, one of them is Spain's, so I couldn't have spread my own religion anyway. Overall, it is feeling really good. I'll have to see how the midgame goes once I'm able to capture someone's religion (or multiple) and end up doing Mongolia's traditional "this continent is mine thanks for settling my cities for me" strategy.
I can't believe I hadn't thought of this strategy for warmongers before. Unless you're someone like Aztecs this seems like a really solid strategy, and AIs now make pretty good religions to steal anyway.