The Empress, much like a lot of modern Republican politicians, was initially manipulating her religion for political gain.
Since the Sethian Rebellion however the crazy has taken firm root in her chaotic psyche.
Thus her Church has gained a deal of power rivalling that of the Guardians, Fleet and even the dreaded Quizzers.
Their theology, a strange mishmash of Shinto and Catholicism places the Empress as a messianic living Goddess who is humanitys only hope for survival. It has never been a particularly welcoming creed and the Empress new paranoia about men hasnt helped in the slightest. This fanatical warrior priesthood is dedicated to purging what it considers evil with holy fire.
Warbands of the Church tend to be split between expendable hordes of Lay Sisters and resilient and charismatic Ordained Clergy. They are tactically uninventive essentially rushing their enemies to close with their flame Weapons however their Fanaticism means where most Warbands just Withdraw they keep fighting, albeit with no idea of friend or foe!