The piety start is perhaps disliked almost as much as the Honor start.
While I find it's normally not as good as other options, it's not quite as bad as that.
But it's still highly situational. (By contrast, Tradition is always great)
Here are the two primary cases I see Piety being decent:
1. Playing Poland seeking Science victory, (who has several policies to burn following completing whichever their first tree is before they open Rationalism. In addition I am going to assume that the advanced option to save policies is off so they can't just store the points and en block complete Rationalism the turn they enter the Rean. era)
In this case, I see a pantheon in which Poland could max out their UA by taking advantage of the Piety - Tradition combo in a manner that boosts science.
Goddess of Festivals (say with 4+ local wine).
First tech to research Pottery
Build a scout, next a Monument, start a worker (or something else) while waiting for Piety opener. Move Shrine to top of the queue interrupting whatever you were building for four turns.
Next social policy should be the one doubling Shrine faith; followed by the one decreasing costs of religious buildings.
When you found your religion, choose Monasteries. When you have enough faith for the reduced price Monastery pick it now in the capital.
If you get at risk of spawning your second natural prophet before completing Piety tree I'd also use it to buy a Monastery in your second city.
Reformation: Pick Jesuit Priests which allows faith buying of Universities / etc.
Second follower: If you think you can finish a full set of Monasteries & Pagodas before reaching education, I'd pick Pagoda; otherwise I'd pick the one giving 2 happiness from the standard temple.
Following completion of this tree, Tradition: Legalism (getting Amphitheaters), Monarchy (solving the happiness issues), and finish the tree (getting free Aqueducts and solving the growth issues)
After finishing all religious buildings, use that massive faith to faith buy those science buildings much faster than you could build them by hand.
Note that the above would also work with Incense, but I find Wine starts to be better than Incense.
A scaled down version could also work with Silver / Gold with Religious Idols could also work (replacing monasteries with something else) but won't be as good due to not having as much faith per turn.
The other case is Byzantine seeking Cultural victory. Say with a starting terriagn in which a normal civ would be torn between picking Earth Mother (for all the Salt resources) and Sun God (for all the Wheat resources).
Here as Byzantine you can select the faith pantheon first and then when you found a religion select Sun God as your bonus belief. Then since you are going Cultural and so will want more slots for artists, pick Cathedrals if still available [otherwise Pagodas] .
Again, after you have the reduced religious price, faith buy in your capital and should you become at risk at spawning a second GP before you finish Piety then buy one in your second city as well.
Upon reforming your religion, pick the Reformation belief that will give you +2 tourism from all religious buildings.
Upon enhancing your religion, pick the most useful religious building left.
You will now get +4 tourism per city in your empire.
Upon finishing the tree, the next tree to go into to secure the Cultural victory is Aesthetics. (Note that going back to Tradition for free aqueducts doesn't work in this case due to how long it takes)
Variations of this can also be used. Like if there wasn't a second pantheon appealing to you, then you could choose religious buildings and a bonus, follower, and second following for +6 tourism per city (if you can build them all and prevent your empire from being converted)
While I find it's normally not as good as other options, it's not quite as bad as that.
But it's still highly situational. (By contrast, Tradition is always great)
Here are the two primary cases I see Piety being decent:
1. Playing Poland seeking Science victory, (who has several policies to burn following completing whichever their first tree is before they open Rationalism. In addition I am going to assume that the advanced option to save policies is off so they can't just store the points and en block complete Rationalism the turn they enter the Rean. era)
In this case, I see a pantheon in which Poland could max out their UA by taking advantage of the Piety - Tradition combo in a manner that boosts science.
Goddess of Festivals (say with 4+ local wine).
First tech to research Pottery
Build a scout, next a Monument, start a worker (or something else) while waiting for Piety opener. Move Shrine to top of the queue interrupting whatever you were building for four turns.
Next social policy should be the one doubling Shrine faith; followed by the one decreasing costs of religious buildings.
When you found your religion, choose Monasteries. When you have enough faith for the reduced price Monastery pick it now in the capital.
If you get at risk of spawning your second natural prophet before completing Piety tree I'd also use it to buy a Monastery in your second city.
Reformation: Pick Jesuit Priests which allows faith buying of Universities / etc.
Second follower: If you think you can finish a full set of Monasteries & Pagodas before reaching education, I'd pick Pagoda; otherwise I'd pick the one giving 2 happiness from the standard temple.
Following completion of this tree, Tradition: Legalism (getting Amphitheaters), Monarchy (solving the happiness issues), and finish the tree (getting free Aqueducts and solving the growth issues)
After finishing all religious buildings, use that massive faith to faith buy those science buildings much faster than you could build them by hand.
Note that the above would also work with Incense, but I find Wine starts to be better than Incense.
A scaled down version could also work with Silver / Gold with Religious Idols could also work (replacing monasteries with something else) but won't be as good due to not having as much faith per turn.
The other case is Byzantine seeking Cultural victory. Say with a starting terriagn in which a normal civ would be torn between picking Earth Mother (for all the Salt resources) and Sun God (for all the Wheat resources).
Here as Byzantine you can select the faith pantheon first and then when you found a religion select Sun God as your bonus belief. Then since you are going Cultural and so will want more slots for artists, pick Cathedrals if still available [otherwise Pagodas] .
Again, after you have the reduced religious price, faith buy in your capital and should you become at risk at spawning a second GP before you finish Piety then buy one in your second city as well.
Upon reforming your religion, pick the Reformation belief that will give you +2 tourism from all religious buildings.
Upon enhancing your religion, pick the most useful religious building left.
You will now get +4 tourism per city in your empire.
Upon finishing the tree, the next tree to go into to secure the Cultural victory is Aesthetics. (Note that going back to Tradition for free aqueducts doesn't work in this case due to how long it takes)
Variations of this can also be used. Like if there wasn't a second pantheon appealing to you, then you could choose religious buildings and a bonus, follower, and second following for +6 tourism per city (if you can build them all and prevent your empire from being converted)
