This is probably the first magic question I’ve asked so sorry if I get anything wrong this time.
In this world, there is a goddess, and she is very, very real. She’s functionally omniscient: whenever a problem, even a highly complex one, is brought to her attention, she can figure out the answer in a matter of minutes if not seconds. She also has the capacity to create gateways between habitable worlds to allow people to explore new lands as well as standard god stuff, i.e. the ability to smite people at a distance, the ability to make seas spontaneously safe or dangerous for ships to travel, etc. Using her abilities puts a lot of mental strain on her, so she can’t use them very frequently (usually less than three times a day), but she’s the only person in the world who actually has god powers.
She also can’t directly communicate with people who aren’t her “priests”, people who undergo rigorous training to be able to hear her voice in their heads as a whisper, and she can’t directly observe the world. She can effect godlike miracles and magic on anyone or anything, but she’s only able to speak or see or hear through her priests. The priest’s connection is also two-way: the priests can hear the goddess and the goddess can hear the priests. This telepathy isn’t constant and requires both parties to actively participate; both the goddess and the priest must be willing to allow the connection to happen in order for it to work.
Her priests themselves also get the bonus that they get special prayer priority: by praying to their goddess for something to happen, they can (almost) always get that thing to happen fairly immediately. Sort of a repayment for being the goddess’s voice; transactionally, the priests relay the goddess’s word to the world and relay the world’s happenings to the goddess, and in exchange, the goddess effects the priests’ will on the world. The result is that the priests effectively have the power of the goddess behind them: try and stab them and they quickly spit “my Goddess protects” and all of a sudden your knife is butter and your heart stops.
At this point in time, a good chunk of the world is ruled by the goddess’s empire, of which she is the Holy Empress. Unable to directly communicate with her empire, she chose the priests to act as liaisons between her and her own empire; other than the goddess herself, the priests hold the highest positions of authority as “one step away” from the goddess. In the absence of communication from the goddess, the priests become the de facto rulers of the Empire, their word effectively law, but are always superseded by anything the goddess says. After all, the priests’ god power is a privilege, not a right: if the goddess learns of a priest’s defiance of their Holy Empress, they lose their priesthood status and are subsequently smote.
The priests themselves serve for life (it’s the highest honor in the land, so everyone’s always eager to accept a life sentence of being a goddess’s puppet half the time), and are selected from the population based on who attracts the most of the goddess’s attention: peasants who do nothing with their lives and idly sit as cogs in the machine and regular criminals are overlooked, and passionate orators preaching the goddess’s infinite wisdom and compassion and selfless caregivers are more likely to be selected. There are rules to being a priest, though:
Priests may not EVER directly disobey the goddess. Obviously. If it comes to the attention of the goddess that a priest has deliberately done something that she explicitly forbidden, or has deliberately failed to do something that she directly ordered, or has falsified her word, the priest has committed heresy of the highest order, and the heretic priest has their powers revoked and is killed either by the goddess smiting them or by whatever guards happen to be around. If the heresy was committed in the presence of another priest or if there are a substantial number of surviving witnesses, then the evidence is considered substantial enough for the heretic priest to be executed. If there’s a very major conflict of interest somewhere, i.e. having to disobey the goddess to save thousands of people, the goddess might decide that the heresy was in good faith and let the priest go free.
No priest can be selected from the same (ideological) section of the Empire as another. Since they’re the only ones who can directly hear from the goddess and the goddess might not always be able to monitor what they’re doing (after all, the telepathy between the goddess and priests depends on the priest allowing it), it’s important that none of them be able to pass off their own words as the words of the goddess. If every priest were selected from the same town, then they all might share common ideas and morals, and then they might conspire to cut off their telepathic connection with the goddess to keep from being caught and then just pass off whatever they want as a Holy Decree. If priests are selected from wildly-varying parts of the Empire (as is required), then it’s less likely for them to be able to agree on anything, so any priest can always tattle on any other for falsifying the goddess’s word, and the heretic priest can then be prosecuted.
Priests can’t engage with regular society except when absolutely necessary. Having the knowledge and power of a god behind them creates a huge power imbalance between them and virtually every other Imperial citizen: were a priest allowed to go about their regular life, they could start committing crimes with immunity, saying that “I’m a priest, you can’t arrest me, our Holy Empress works in mysterious ways”; denying a priest is considered heresy, and if the priest doesn’t actually directly disobey the goddess, then they can kind of do whatever they want. As such, priests are separated from the rest of society in their own palaces with dedicated servants, leaving the palaces only when they need to communicate with the goddess or relay something important to the Empire.
There must always be exactly 25 priests. This is because, uhm… uh…
Therein lies the question: Why must there always be exactly this many priests, never more and never less? One might argue that having more priests would be advisable, since it would make it harder for a group of priests to conspire to falsify the Holy Empress’s word, and it would also allow for the goddess to more efficiently communicate with her Empire: if there were more priests then each priest would have to visit fewer towns in order to communicate a decree to the entire Empire. But for reasons, there has to be a finite and very small number of priests. Why is this?
Note: 25 is a fake number; the number could be higher, could be even lower, but the point is that it’s very small compared to the population of the Empire, less than 100.