The Imperial Church is a convenient umbrella term for the federation of regional religious structures whose members are generally regarded as the rightful spiritual shepherds of the Imperial religion.
In theory, the Imperial religion remains united in one great church, as it was in the days of the Empire, but in practice it has long since become decentralized - though, it must be said, much less so than the former Empire has politically. The entirety of the former Imperial sphere largely remains divided up for religious purposes into units that either are, or are based on, the ecclesiastical provinces of Imperial times.
Within each province, the organization of the church is both vertical and horizontal: vertical, in that each territory or major locality requires its own local administration; horizontal, in that while temples of the Most Eminent are theoretically supreme, those of Her Court are self-administered. The result, when decisions must be taken at the provincial level, is that church government takes the form of synods with a complicated committee structure. Each territorial subunit of the province sends seven representatives, one from its main temple of the Most Eminent, one each from the main temples of Her Court of six consorts. The priests of each god will form committees on matters that are of particular interest to their temples, while matters pertaining to only particular localities may form committees of all those localities' priests - though decisions are expected to be brought before the synod and approved there before taking effect. Synods are generally presided over by the High Priestess of the Most Eminent of the see of the province, though what authority this carries is mostly moral and admonitory.
An analogous process applies to the governance of the church as a whole, with an occasional grand synod being held on the Hallowed Isle near the ruins of Kar Iitan, the former Imperial capital. These events, however, are extremely infrequent, rarely occurring more than once every few generations, and so while the High Priestess of the Most Eminent in the Delta retains a certain primacy as the seniormost cleric of the church, it is almost entirely honorary except on those rare occasions.
Many of the remoter regions adhering to the church are independent in all but name. They are too distant from the old Imperial core to either reliably participate in a grand synod or to have its decisions effectively forced on them, and therefore despite a theoretical allegiance to the shared traditions of the church, often tend to diverge in the specifics of their practices. This is particularly the case in the brightness, where the provincial structure was never strong, with a concentrated takma population that is relatively isolated from the cerulean_tangle. Going by ship is easily the least difficult method to reach the region, but given the near-monopoly of the Abethines on long-distance sea travel, there remains a significant barrier to the flow of ideas and communication.
In essence, the purpose of the Imperial religion is to ensure that the siathar are remembered and worshiped properly. Its main emphasis is on orthopraxy rather than orthodoxy: that is to say that one's local priests will concern themselves extensively with how one behaves toward the Siathar, but not so much with faith or belief. One who follows the Siathar does so by their conduct - whether they attend ceremonies, whether they offer sacrifices, whether they make donations to local temples. While actually making public statements against the Siathar would be considered beyond the pale, a quiet disbelief in their literal existence is not especially heinous.
The emphasis on practice translates into a certain tradition of charity and service, especially among the temples of the members of the Court. While the emphasis varies from place to place, the charities and institutions based around the temples are in many cases the closest things to public services that many takmar receive.
The spiritual authority of the temples, and their broad geographical organization, also makes the church a player in politics. On a local level, it is often broadly popular with the population and can leverage public opinion for or against a ruler; internationally, it is generally enough of a neutral party to dampen conflict (or direct it, if a state is acting against their interests).
There have been occasional attempts to form theocratic states, but the polycentric nature of Imperial religion tends to make the merger of church and government a difficult maneuver. Overall, the church has found it more profitable to act as a mediator between rulers and ruled, to benefit from the goodwill of both without the responsibilities of either.
The church plays no role in the worship of the lamnar. While some may claim to have their favor, the general consensus is that the Lamnar are too capricious for such claims to be reliable. As for the priesthoods of the Siathar, their attitudes toward Lamna-propitiation vary between ignoring the practice to discouraging it, though only those whose live comfortably amidst civilization generally dare to do the latter.
During the latter days of the Empire, the Imperial Church was technically headed by the Empress, who was the living representative of the Most Eminent in the mortal realm. In practice, however, the Empire in its vastness forced a certain measure of decentralization on religious affairs, as it did on political control, and the various provinces were responsible for their own day-to-day administration and the implementation of the Empress' directives.
The collapse of the Empire, therefore, resulted in less disruption for the church than for other institutions, and although the physical wars of the period took their toll - as did the flowering of new religions and cults - it has bounced back in recent cycles as a force for stability.
The institution of the Empress still occupies a certain role in the thinking of the church, which considers the position merely vacant rather than ended, and more than one descendant of the old bloodlines has harbored ambitions of ascending the throne with religious support, so far without success.
At the core of Imperial mythology is its creation myth, which describes how the first deities, seluurin and khezri, begat the lamnar - the cosmic and nature deities - last among whom was the goddess of life. For their youngest child, the Two Highest created the world of avishraa for Her creations to dwell in, and She and her husbands and children - the siathar - work constantly to lessen the weight upon the souls of takmar, so that they may rise up after death to join Them.
The myths that remain focus largely on the role and history of the Empire, embodying - as it was held to do - the values of the religion and promoting them in the world.