Mothon is considered a Demon Cult by the other religions. Each City has their own archetypal deity with lip service being paid to the other deities of the pantheons. These official churches have big temples, public worship, the endorsement of the government, and the weight of tradition. However, any magics they produce are just that magics, not miracles. So these priests use a magic system, just like any spell caster.
Mothon is called The Spirit of the Darkness. That is true, though not an appealing name. It was “he” that was the primal darkness. He created space, light, and time. He created spirits by seperating Mothon and Not-Mothon. He created the world, the stars, and the universe. He created time and set things in motion. He created spirits to balance the material.
Mortals created all this other stuff that was not in his plan like oppressive governments, slavery, organized religions, and so on.
Mothon is not a friendly god. His image is that of “Evil”. Though the visage is frightening, it is the truth (accurate). Mortals seem to judge by appearance. He is neither “Good” nor “Evil” as those are Human Constructs. He is the supreme Order Bringer, being the creator of the universe. Yet, he does not set down Law. That is not his view of Law, that is Human’s view of Order and Law. Mortals can not understand Mothon directly, they do not have the perspective and the knowledge of the Great All. They can only understand Mothon through analogy and by what Mothon is not.
Mothon does not require worship. He is not a weak thing requiring the adoration. The Worship of Mothon is secretive and personal. It is all about the contemplation of the Eternal Dark and One. Those that follow Mothon receive the ability to create “clerical” miracles, to alter reality slightly to fufill Mothon’s will. Small groups gather together to discuss their meditations and contemplations of Mothon. Together these groups quietly seek The Truth.
Of course, other priests call him a Demon. That he grants inhuman powers to his worshipers, rather than proper spells. Mothon worshipers are hunted by the government as subversive. Those who have a vested interested in the falsehood produced by mortal made religions wish to obscure The Truth of Mothon.