At the height of the Empire, great cathedrals were built and the priesthood grew strong. At the head of the institution was the Patriarch. This spiritual leader was selected from the pontifex when the old leader died.
The faithful depended on the church as much as the throne for succor and guidance. This twin poles were not alway in perfect accord. Sometimes emperors and patriarchs would clash over the issues of the day. Sometimes violently. More than once church templars took the field against imperial troops.
With the empire's decline, the church maintained its hold on the faithful, but politically it now had to juggle relations with multiple rulers instead of just the emperor. As a result, the prelates of areas like Peledan and Blackport have become more independent of the Sacerdom (the enclaved seat of the Patriarch in Rike). In the Splintered Princes, the church is strong among the people, but there is no central ruler to appeal to. Local priests have varying levels of influence with the petty lordlings that rule the various territories. Oddly, the church's political influence seems weak in Silverrun, despite the presence of the beautiful Winged Cathedral and a more stable social structure than the bulk of the region.
The core of the faith centers around the concept of illumination, or the opening of one's being to the light of the divine. The pillars of worship center on spiritual purification through piety and devotion to the church and its teachings. These include tithing as well as avoiding sinful pride, dishonesty, excess, and brutality. The faithful attend weekly services for blessings and to make regular confession. Priests perform these services as well as marriages, funerals, and the anointing of children into the fold.
There are some priestesses, but the overwhelming majority of the clergy is male. There has never been a Matriarch of the church, nor even a female prelate or pontifex. In addition to the ordained priesthood, there are also cloistered monks and nuns, as well as mendicant friars who are considered "of the radiance."
The templars are militant, chivalric orders that have cropped up from time to time in the church's history. The church does not actively support such organizations. Traditionally they have been comprised of privileged faithful, who have banded together –usually in times of crisis– giving the church a militant arm to wield. The would be templars must obtain the charter from the Patriarch to become an official order. At which point, they gain a certain status within the church hierarchy. The charter can be revoked at any time, so many orders have only lasted for one Primacy (or less). At present, there is no "active" templar order, though many nobles still claim a connection to some historical ones.
It should be noted that while the church is the official faith in the empire and Peledan, it is not the only religion. Nature worshippers, demonic cults, and other beliefs hang on in the fringes and shadows of society. The church is a distinctly human religion as well. There are no significant populations of nonhuman followers, though individuals may have adopted the faith.