Many belief systems have come and gone throughout Outer World's history. Each aeon brought in new ways of thinking, and with it, a cataclysm that overthrew some existing power or eroded away a status quo once taken for granted. The current world is characterized by the swirling mixture of remains of divine law, scattered eldritch powers, tattered fate, and the ubiquity of the arcane. It is an overwhelming, but nonetheless wonderous place that calls to be understood. Scholars, leaders, and overthinkers have tried their hands at making sense of it all, and some of those thoughts have actually stuck.
It should be noted that while all of the following belief systems have dedicated adherents, the average individual mixes and matches aspects of these teachings in the way that suit them best. Many find Outer World to be too strange and chaotic a place for a single cosmic truth.
The Mana Inequity Principle and Arcane Altruism
A stark reality of Outer World is that certain individuals can do things that others cannot. Seasoned casters will spend their whole life studying to master a few spells, while some cocky hedge wizard will have just as many under their belt with a fraction of the practice. Veterans of multiple wars will watch in awe as a youthful waif leaps along rooftops and displays master level swordplay to topple a flying beast they couldn't touch, and so forth.
Both light and dark mana flow through all things, but it lingers longer and empowers certain individuals more than others. This leads to heightened physical ability, rapid personal growth and supernatural talent with magic and other skills. This obvious difference was noted by a group of 2nd Aeon researchers, who also named it the Mana Inequity Principle.
While these facts are easy to see, a question remains: why does this imbalance exist?
Early assumptions attributed it to spiritual enlightenment or being chosen by fate, but ancient studies and modern observation have proven that mana attunement is not connected to these factors at all. In fact, there seems to be little or no consistency between those gifted few. Magic is as alive as any of us, after all, and is just as subject to whim and capriciousness as the folk are.
There remains a debate as to exactly what a mana attuned individual should be doing with their gifts. The most popular contemporary answer is “Whatever they like”. In a close second is the primary edict of Arcane Altruism, a philosophy created by prominent Akenian sage Dizah Gren.
It proclaims that all magic, including that which is under the power of an individual, should be used for the betterment of all folk. Dizah's initial intent was clear: she was a firm believer in using her power and knowledge to improve the lives of those without and felt others should aspire to do so as well. A rival wizard named Gar Baxin liked the sound of her teachings, but argued that to truly do the most good casters must first accumulate a great deal of arcane might, leading to the well intentioned doctrine becoming an excuse for some to attempt dangerous rituals and hoard powerful relics.
While it fell out of vogue after the 3rd Cataclysm and the fall of Akenia, Arcane Altruism has seen a recent resurgence, predominantly in Shard's college of Magia. The Gren and Baxin schools of thought came along with it, and that debate has also resumed.
The primary tenet of this philosophy is that the light of the Sun Machine is a shepherding force, essential for living a full and proper life. The Invincible Bright is anthropomorphized as a benevolent force, blessing the Sun Machine and all those who wield Bright Magic with the strength and wisdom to keep the folk on the path of truth.
Obfuscation and ambiguity are regarded poorly, as a lack of clarity is seen as the primary obstacle on the path of enlightenment. Some of its observers are loyal to Emperor Regulus, seeing him as an embodiment of the Orthodoxy's principles in Outer World. While he had little to do with the founding or spreading of their beliefs, he's yet to deny this beneficial assumption.
The Speakers of Sol represent the main driving force of the Dawn Orthodoxy. Centered in the Sol Alliance, their spirited words ring especially true in light of the Sun Machine they so proudly revere. They lack a particularly strict hierarchy, giving each speaker equal authority on the subject of their religion and leading to a great deal of factions under the Orthodoxy's umbrella.
Followers living in regions not graced with the light of the Sun Machine are known as the “Splintered”. Many will never see the brilliance they so admire, contenting themselves with Star Shards and other sources of illumination while hoping their essence can join the Invincible Bright upon death. Their practices tend to be a bit less bombastic and softer than the Speakers of Sol, but they are no less dedicated.
Often dismissed by detractors as the whisperings of those lost to ambition and egoism, Dark Adventism is actually a rather complex and flexible set of beliefs. The Profound Darkness and the embrace of one's innermost self is at the center of its ideology. Expression is a most holy act, with both great works of art and blasphemous displays owing their existence to this philosophy.
Denial of one's emotions and desires or those of others is against the ethos of Dark Adventism, but like the Profound Darkness itself this edict is mutable and interpretable. Those truly devoted to the philosophy fully embrace the contradictions that come when one's wishes intertwine and conflict with another, seeing them as quandary worth pondering and a test of conviction.
Most dedicated practitioners concentrate on personal agency rather than grand sermons. Known as the Tenebrous Pact, its adherents seek their greatest selves by whatever means they can manage. This private path is popular with all walks of life, attracting everything from ambitious merchants and artists to skilled warriors and phantom thieves.
A more controversial form of Dark Adventism is Nephelism, named after the celebrated Shadow Queen of old Calian, Nephel. Based predominantly on her actions and teachings, it eschews the abstract aspects of the philosophy and puts a greater emphasis on dark magic as an effective means of attaining one’s desires. Nephel herself had a well documented fondness for summoning entities from beyond the sky to do her bidding.
The Twilight Manifest
Moderation and balance are the core virtues of the Twilight Manifest. Both the Invincible Bright and the Profound Darkness represent various forms of excess; problematic but necessary. It is good and proper for one to maintain parity in their various whims, usually with the help of self-discipline or a spiritual leader.
Excess is seen as the primary sin of the folk, one that even the most pious will occasionally falter in. Many teachings of the Manifest suggest seeking balance via calm contemplation on how best to harmonize their immodest tendencies. Some will even suggest to attempt equal but opposite actions to achieve true equilibrium.
The Twilight Manifest is gently practiced in many places of the Outer World, seen as a guideline rather than a strict code of ethics. It is often adopted by those reaching the later years of their life, as the moderation it espouses is seen as a good way to keep healthy and safe.
More structured versions exist, however. The Church of the Sacred Chain is the most prominent faith in Shard and encourages strict enforcement of its doctrine, going so far as to accept donations to their institution as a means of "balancing" one’s immoderations. This has worked out well for the church, allowing them to grow into a powerful organization and even fund their own knightly order.
A final note...
This is not an exhaustive list of the philosophies and religions present in Outer World. For example, the religions for the various small gods, immortals, and un-shaped that have bothered to gather a following are missing, as are the teachings of those loyal to the deposed Divine Rulers and the remnants of their Celestial Order. There are also further sects and branches in the philosophies listed here. Attempting to list all of them would be an arduous task indeed.