Religion in the Graylands
It may seem as though since we have already seen that there is a multitude of deities on the side of Law and Chaos, that there must be a multitude of religions. This would be a misconception. There are really just two main religions in the Graylands. Law and Chaos are religions. They have different pantheons which have different sects built around the individual gods but when the time come for war, the sides are Chaos and Law. There have been many Crusades on both sides and whenever the Lawful world is under attack, the adherents of Law come to defend it. The hoards of Chaos have a more complex relationship to one another, but, in general, when one sect is under attack, others will come to defend. More often than not, Chaos is the aggressor, however, because it is far easier to rally Chaos worshippers when you offer them the chance to smash and burn things. Old texts like the Eternal Tome offer this often forgotten dichotomy between Law and Chaos: "Beneath the rule of Chaos, the strong consume the weak. Bathed in the light of the Eternal Law, it is the strong who protect the weak."
The Grand Ticking Church of Timekeeping Decachrontatus who turns the Grinding Gears of Reality
This is a Lawful cult whose power base is in our own Phaidecia. Its beliefs about Law are best described as "For all things, a place and function." The priests of Decachronatus believe that each person is a cog in a cosmic machine and perfect order will be achieved when each person submits themselves to their preordained purpose. This does result in a rigid class structure. Social mobility is not just distasteful but can be considered sinful, though there is some theological bickering on this point. The church is also laid out in a strict hierarchy and it is only by incredible ability, effort, and divine mandate that any cleric ascends through the ranks.
Most of the cities of the Lawful sects find themselves in the heartland of the Civilized Lands but the Church set up in the land that would become Phaidecia because there the first Wands found the staves made from the bone of the Storm Leviathan. There Decachronatus appeared to them and established his church on the site where he slew and buried the beast. Phaidecia then built itself around that holy site.
The Red Temple
In Redrum, the Red Temple stands as a defiant thorn of Chaos in the side of the Wands. There the Hidden Lord and Cadixtat, the Chaos Titan, are worshipped with human sacrifice and orgies. The Red Temple Cult is a weird group of oddly stuck together sects. Like most things in Chaos, organization is next to nonexistent. There are occasionally quite odd fusions as a result. The two sects both believed that the land taken by Phaidecia was sacred for different reasons. Cadixtat's mother was the Storm Leviathan. The Hidden Lord's reasons are his own. The two sects decided that they both hated the Phaidecian, so they decided to build a great big middle finger together in the form of the abominable Red Temple. The Red Temple Cult believes exactly the opposite of the Grand Ticking Church out of spite. Whereas the Church believes in a rigid social order, anyone can get anything they want in Redrum through the act of murder. You want this guy's bar? Kill him. You want to step up the clerical hierarchy? Kill the next highest priest. The Red Temple priests are not really very organized but there are some remaining clerics that still hold to the original plan of the Red Temple Cult to destroy Phaidecia.