The Cult of the Holy Mother is a female-dominated sect within a larger religious organization led by a male patriarch. Although the cult is small, it retains a significant role in the imagination of the populace. The cult is made up of priestesses that enter into holy matrimony with their deity. These women have taken vows of chastity to devote themselves to the study and correct observance of religious rituals. There rituals are deemed necessary by the organization and forbidden for others to carry out. As such, they are regarded as fundamental to the continuance and security of the state. Occasionally, a supernatural event will be triggered which is described by the org. as a miracle. A priestess will be chosen by their deity to give birth to a son, who will grow up to be ordained as the next leader of this faith. These miracles occur anywhere from every few decades to every few centuries. They serve as an expression of the god's power and authority over nature, as well as a reminder to the people of the contract between the deity and mankind. This event symbolizes the holy trinity that the religion bases itself upon, with God the father in heaven, God the son as his representative on Earth, and God the Mother as the intermediary between both worlds.
Miracles can be used to legitimize the authority of religious leaders and authenticate the special relationship between them and the deity they worship. These supernatural events confirm the truth of the faith's teachings and secures their place in society. If done too often or on too big a scale, the populace can begin to take them less seriously as miracles and more like magic. They may even begin to demand "magic on demand" from their leaders to solve specific issues, and may even turn on them if they can't deliver. The trick is too make them rare enough so that they are seen as powerful events when they happen, but common enough to remain in public memory. However, other factions within a religion who desire more influence over the faith's direction may claim their own "miracles" as a source of their legitimacy. This can be marketed through events that retain some significance in public consciousness, or lost "sacred artifacts" that have suddenly been re-discovered, such as a shroud or an ark containing golden tablets. This can ultimately lead to a schism within the faith, with the religion breaking up into various factions spread throughout the nation, declaring themselves as the true faith and the others as heretics. In addition, rivals outside the faith would question the legitimacy of the cult's miracles to weaken their image in society, suggesting that the priestesses simply broke their vows and that they are merely fraudulent acts meant to deceive the public. As there is no simply way to disprove this, it can be a blow to their legitimacy.
How can the cult of the Holy Mother use their supernatural miracle to prevent schisms within a religion and keep it unified?