Belief in the creator goddess, Akasha, is a common theme on Mara. It is present especially in Aduro Aurum, which houses the temple, a large religious organisation that preaches on her behalf. Most of Aduro Aurum's population believes in Akasha, and even those who don't tend to stay quiet about it; the city is a theocracy, and the temple deals harshly with anything it views as blasphemy.
The temple tells of a time when none possessed magic, and a great disaster befell the ancient city of Arcis. Recognising the need her most faithful creations had for magic, Akasha gave them the valui, and using that they built Aduro Aurum. To this day the valui are still revered as a gift from the goddess, and innate magic users are considered a blessing above all else. As a result, those innate users who are born within the city are taken by the temple and raised to become priests, or to serve Akasha in other ways such as by becoming bodyguards for the rector.
The Aequitas, currently the only other large group on Mara, also believe in Akasha. Their legends are much different, however. Contrary to what the temple says, they claim that at one point in time everyone on the island had magic of their own, and that the priests of ancient Arcis, growing too self-important and greedy, had angered the goddess and caused her to strip their elements from them. The valui, they say, are nothing more than a weak substitute for what everyone had before they fell out of Akasha's favour.
Predictably, relations between the temple and the Aequitas are hostile at best; a priest coming onto Aequitas territory would certainly be killed, while a member of Aequitas entering Aduro Aurum would likely be arrested and executed for heresy.
Outside of those two, however, things are more lax. Those who live out in the wilds, away from Aduro Aurum and Aequitas, lack the protection they offer to their citizens—but they are also free from any stern religious demands. They may believe or not believe in whatever they wish, although most of them at least know of Akasha.