This is very rough, but I like where it's going:
The Barsinian Empire dates back about 350 years, and is comprised of the core kingdoms of Barsin, Eria, and Kihronia- but the Holy Barsinian Empire is only about sixty years old, and emerged when the current Empress, Eurissa, began to rapidly expand the Empire’s borders after coming to power in her early twenties. There are currently about twenty kingdoms on two continents that are part of the Empire, and there are at least three wars on various fronts to add more.
Eurissa was born from the previous Emperor’s fourth wife, and claims she is the Goddess Incarnate (the second person in history to make that claim, the first being the progenitor of her bloodline on both sides), and as such is pledged to remain a virgin, with the whole world as her children. More pragmatically, she killed all her father’s offspring from any woman not her own mother. These siblings were allowed to live with the expectation that one of them would breed an heir for her.
The state religion of the Holy Barsinian Empire is monotheistic, following a mother goddess called Mahle, whose symbol is a green bear, and who speaks only to children. As such, all the oracles are pre-menstrual girls, and boys whose voices have not changed. The priests and priestesses are men and women who have spent years studying how to interpret the oracles’ visions, and generally come from the noble families of Barsin. After Eurissa assumed leadership of the church, she decreed that males could be kept holy via pre-pubescent castration, which has created a new class of priest. She herself does not and never has menstruated, which is part of her claim to divinity.
Although Eurissa remains both mentally and physically sound, her advancing age (she’s now in her mid 80s) is increasing the court’s desperation for her to choose an heir. She prefers to keep her various nieces and nephews at one another’s throats, demanding greater and greater feats of martial prowess to impress her. Her goal is to bring literally the entire world under her emerald bear pennant, preferably in her lifetime, so that all can enjoy the protection of Mahle. Conversion is required to become a full citizen of the Empire, but a ruler may convert on behalf of their people. Eurissa herself isn’t overly concerned about the common people following Barsinian protocol to worship Mahle- She is the Goddess whether they truly believe or not- but some of her governor-priests can be a little more zealous. What Eurissa does concern herself with are taxes and warm bodies to fuel her armies, and great minds to develop more and better war machines.