Myth of Creation. Aca-Santerran beliefs are based on the following myth of the divine Twins Fekhath (Silence and Truth) and Faenwo (Creation and Hope) who formed the world when fighting each other:

"A long time ago the Twins Fekhath and Faenwo fought for the dominance in an empty universe which their mother Marjalla (the time) said will be once filled with incredible sources of power and lesser beings needing their guidance. As both brothers argued over the way how to split up the universe and how to await the arriving of these lesser beings both fell into rage and started to fight each other. Soon the void was filled with their blood forming clouds and spheres of matter and energy but the brothers didn't cease to fight. They summoned powerful creatures from the depths of their own souls to fight each other and soon the whole universe was set on fire. The matter was forming huge sparkling masses in space and the energy was flowing through it. The Twins gave more and more of their powers to their fighting spirits and summoned even more minions to kill each other. Slowly a huge mass was forming occasionally reshaped by the powers of the battle and by the energies around it. The sparkling spheres called 'stars' were circulating around it. The mass turned into a disc with mountains and valleys, oceans and magma but the brothers continued to fight. And after another eon the first being emerged from this plane of existence looking down on a chaotic landscape. It looked up to search for its possible origin but it was futile! Hanging dead in the sky were two spheres of destruction enlightening the world. The Twins were dead..."

-- "The Chronicles of the Elder", Library of the Temple of Barkhas, Altyr

The consequences of this mythological story are recounted by Merdocan the Blue from the Library of the Temple of Barkhas in Altyr:

"At the moment the Twins died the armies of both ceased the fight shocked about what just had happened. The Twins gave too much power away and grew mortal, able to be killed. In their confusion and pain the great warriors pleaded Marjalla for guidance but she remained silent. So as the Gods saw that lesser beings were crawling over the surface of a worn out world they decided that when these are the beings Marjalla ordered her children to guide they themselves as the next higher beings in place have to fullify the fate. They went to the world beneath them and took land to rule and form and gathered the people around them to guide them. Barkhas ordered the snake Ulieth to encircle the world to hinder the waters and drifting lands from falling into the Void and breaking apart. Angus forged the sky to capture the air and Narvi fixed the lands onto the bottom of the sea and forged the plane the world is based on."

--"The True Path" by Merdocan the Blue, The Library of the Temple of Barkhas, Altyr

It is said that with the death of the children Majalla withdrew into the Void that surrounds the world and only the Aca-Tar, her loyal followers and the Aerynian, their servants, remained to establish the order Majalla has meant this place to be. And only the Aca-Tar and the Aerynians are meant to travel the Void beyond the world.

Deities. The Santerrans differ in their worldview between two general kinds of Gods, the Aca-Tar and the Aerynians. The Aca-Tar are seen as the High Gods of the world who took the reign of the world after the departure of Majalla. They're the most powerful forces in the world and command the Aerynians who fulfill certain tasks to make the world work as it is. However as the Aca-Tar and the Aerynians are both descendants from the fight between the Twingods they as all creatures in the world suffer from the failure of the Twingods and are in a way not perfect, not omniscient and not omnipotent. Thus they forged a great hierarchy to keep the world in balance and split the responsibilities among each other.

The Aca-Tar (High Gods). These powerful beings - in the belief of the Santerrans - rule the world and keep it in balance. In the Santerrans belief they as much rule over certain elements of life as over certain territories of the world. Barkhas is in their eyes the preserver of the world and the strongest God because it is him who keeps the oceans of the world together. The Aca-Tar are androgynous entities and the most unaffected by the war that destroyed the Twingods though often they're referred to with gender because of the way these gods appear to most mortals.

• Barkhas, Lord of the Thundering Depths
  Barkhas is worshipped as the protector of the kingdom of Aca-Santerra and as the Lord over all oceans of the world and the lands that swim on them. Legends tell that he once led the ancestors of the Santerrans to the shores of the islands that became the homelands of the Santerrans.
  
  Barkhas reigns the depths of the sea and the coasts of all lands bordering his ocean. For the safety of the kingdom every year many sacrifices and prayings are done at his main sanctuary "Aca-Wyr" which is said to be the top of his legendary sea palace. In water the Santerrans see the blood of the world as the water bows and bends and changes at every moment.

• Angus, Lord of the Winds
  Angus is second only to Barkhas. He obeys to noone and rules everything from the mountain peaks to the farthest end of the skies. All birds are at his command as he can blow the winds to any direction and any speed.
  
  He is seen as the protector of Altyr which is his main sanctuary as well. The temple is famous for the "Windsingers" who are said to have power over birds, the winds and even the storms.

• Retarra, Goddess of Fire
  In ancient times she was mainly worshipped as the Goddess over the hearth fire and the home but later developed into the Goddess of Smithing and Craftsmanship and soonafter into the Goddess of Wisdom and science. In many ways she is said to inspire the mortals and generation for generation reveal more to those that seek to understand the world around them. Today you could say that she is the Goddess of the Mind, most interested in educating the mortal beings and giving them means of protection.
  
  Her sanctuary is the vulcano on the island of Jarka. The "Firedancers", the priesthood of Retarra, is said to have the powers to control the fire in many ways and ignite the hearts and minds of any around them.

• Narvi, God of the Lands
  Narvi is the God of the Lands, the Earth and anything prospering on it. He is the Beastmaster as well as the Tender of the Forests and the Lord of the Mountains. He secured the lands which swam freely on the oceans and made them stable islands of life capable to compete with the realm Barkhas created undersea.

• Thalisien, the Dreamstalker
  No temples and only few people worship this God in rituals though he is among the strongest of the Aca-Tar. But where most Aca-Tar took a seat in the various parts of the world his interest lies not in shaping the world but determining its fate. Thus he is travelling in the void outside the world to seek for knowledge far away from Caelereth. He is even said to council Majalla who has left the world on the death of the Twingods. In his role he is alone, without the many followers other Aca-Tar have aquired among the lesser Gods he only seeks those he needs to talk to.
  
  In the eyes of the Santerrans he has the power of foresight and the few mortals he blesses with his spirit are known to be outstanding seers among men. He has no sanctuary in a temple but it is said that sometimes when great things arise he steps into someone's dreams to tell about the future that will be coming.

• Mari, Goddess of the Underworld
  Mari is seen as a Goddess that lures in the dark corners of anyone's mind. She is the Mistress of the Dreams and Desires and in that matter can haunt the mortals and torture them with incredible cruelness. She is said to oppose Thalisien who seeks the truth of the world's fate and wants to change it instead. Like him she is not worshipped in many great temples but is still respected as a powerful Aca-Tar who might fulfill one's dreams... or destroy you. Insanity is often seen as sign that one was touched by this Goddess.
  
  Mari was an Aca-Tar who was not worshipped by the Santerrans till they conquered some of the Murmillion tribes and was not recognized as one of the Highgods before the Year of Darkness. In that year she also became a new aspect. Beyond her devastating beauty and her cruelity in betraying one's heart but she earned also one positive aspect: She is also the Goddess of Hope, waking ones lowest instincts to prevail when even the mind has given up everything.

The Aerynians (Lesser Gods). Following the Aca-Tar in the hierarchy and serving one of the Highgods in certain aspects of their realms are the Aerinaen. They're usually represented as the children of the Aca-Tar and are closer to the mortals though themselves still to be considered nearly immortal. Other than the Aca-Tar they usually have a distinctive gender and serve the Aca-Tar as their followers in the world, sometimes even showing themselves as messengers to the mortals. The relations of these lesser deities often reflect the hierarchies in which the Santerran see the world to work in.

Most Aerynians are somehow aligned to a certain Aca-Tar, most even seen as their children, but as they're many they'll be explained in conjunction to the Highgod they serve.

The Wergan. The Wergan are another part of the etherial order of the world. They appear in different shapes and sizes and their agendas are even more complex than those of the Aerynians. They obey to the orders of the higher order and often appear to accomplish certain tasks to them. The kinds known as high demons to the Santharians are seen as Wergans but also so immensly powerful beings as Ulieth, the mythical snake encircling the world with its body. The Wergan are often prayed to as they're the most likely to do the mortals a favour - for a price. In many rites they are meant to protect houses from fire, warriors in battle and bring health to the ill. The success in these issues is of course varied as the Wergan cover all facets of characters the mortal races show.

Legends. The Santerran myths and legends evolving around all the Aca-Tar and in even greater complexity and length around the Aerynians are too many to count. Many historical events are explained in Santerran mythology with the presence of one or the other high being. Great tales and small ones are told throughout the High Kingdom all displaying the existence of the divine, but also its failures and the failures of men.

However, the most important legends are those around Thalisien and Mari who are said to continue the dispute of the Twingods on a different scale drawing all the Aca-Tar in the intrigues and matters of the world.