The Cycle and Oroborites

"May the cycle turn in your favour!"
- Common saying in Emrath
The most common mythos in all of Erden is a set of beliefs referred to as "The Cycle". Most civilizations, with notable exceptions, feature this as a central part of their beliefs and folklore, while some have expanded this belief with additional gods. The exact nature of this varies across cultures, however. In some regions, this belief may manifest as a simple belief that time and history tend to repeat itself, while other regions feature the Cycle as a central part of their state religion.
In general, a few common threads of belief hold true across the continent. Firstly, there is the belief that time follows a cyclical pattern, that history repeats itself over and over across the eons, that widespread destruction is followed by brilliant rebirth. Secondly, there is a belief that the turning of the Cycle is driven by conflict between deities, good and evil. This repeated struggle between gods, a veritable War in Heaven, is responsible for the cyclic pattern of history, as gods repeatedly rise to power and are overthrown over the millennia. Lastly, some folk have adapted the belief of the Cycle to the very fate of their souls, believing that their spirits cycle through material, ethereal, and celestial planes.
The most common form of Cycle-worship in Erden is that of the Oroborites. Oroborites believe in a world-snake, called the Oroboros, which venerates the natural cycling of nature, time, life, and death itself. The Oroboros takes the form of an enigmatic serpent eating its own tail, and is known to be aloof and never communicate with its followers. Oroboros worship is common in Emrath and various druidic religions, as well as the Lumeric Pantheon.
Along with the Oroboros, the two other most common deities in the Oroboritic faith are Lathandar and Kelemvor. Depicted as offspring of the Great Serpent, Lathandar is the god (or goddess) of rebirth and the sun, while Kelemvor is the god of death and the moon.

Variations & Mutation

The Lumeric Pantheon 
The state religion of Lumeris is the most common and organized of the Oroboritic faiths. The Lumeric faith holds that through the breath of the Oroboros, the sun goddess Lathandar (AKA the Morninglord) and the moon god Kelemvor were created as her children, forming a holy trinity. Lathandar, goddess of rebirth and light, is especially prominent in Lumeris, where numerous sun temples and gold-masked priests can be found extoling her virtues.

The Oroboritic Orders:
There are many organizations that worship the Oroboros, and some are vastly different from each other. In general, all Oroborite orders venerate the Oroboros to a varying degree, incorporate serpentine imagery, and tend towards nature and asceticism. Beyond that, there are dozens of orders with significantly different beliefs. 
The Keepers of the Cycle:
Among the most powerful yet secretive of the Oroboritic orders are the Keepers of the Cycle. This shadowy group has established itself in numerous temples and fortresses across Erden, many of which, such as the Amber Temple, are storehouses for knowledge and magical artifacts. The Keepers of the Cycle oppose Sanguine and her followers by subtly guiding mortal civilization from the shadows.