During the long, dark reign of Li Kong Zhuan, The Bloody Tyrant, religion and worship of deities was ruthlessly surpressed. Those who broke this law were often tortured for the names of their fellow worshippers, then tossed into the ghoul pits to be eaten alive. This violent surpression led to the vast majority of religious rites and prayers being lost over the centuries, with only a handful of ancient religious relics and scrolls surviving to the present day.
The religions still extant today are those that managed to survive either as underground movements or in lands beyond the borders of the Empire of Bloody Tears, hording the few scraps of religious writings that they had or relying on oral tradition. With so much knowledge and religious wisdom lost to the iron fist of The Bloody Tyrant, the current temples of The Shudan have taken to funding archeological digs and reliquary delves to reclaim some of their lost glory. Many young would-be warriors and scholars have started to travel far and wide in search of lost lore, hidden relics and secreted holy places of The Shudan in the hopes of gaining favour with the gods or access to the special healing magics of the temples.
Some of the most sought after rituals are those that heal the most grievous of injuries to body and soul and, some whisper, even allow powerful priests to resurrect the dead. Were these to be found, the finders would gain a huge bargaining chip with the temples, not to mention attract the attention of the rich and powerful. Despite not having some of the most powerful of healing magics and prayers of millenia ago, the temples have gained a great deal of power and wealth since The Blood Tyrant’s fall. The little healing magic that they do have is faster and often capable of far more than the herbal remedies so common throughout the empire, though many of the temples also provide the herbal remedies as well.
See the Deities of Keimusho for specific details on the major religions. Many other entities are worshipped the world over, though these are sometimes viewed with suspicion as many a corrupted spirit that once owed allegiance to Li Kong Zhuan has fooled mortals into providing gifts and sacrifices to their dark appetites.