The Old One is the living core of Tarrod.
Midian is a dark fantasy game. Most churches in Midian are moral belief structures & guidelines rather than a system that contains a deific figurehead (or many such) and an afterlife.
Context: The gods of Zetacron are physically present in the world. You can go and meet them if you like. Additionally, they are very human, with flaws and quirks—possibly more than regular people.
When the Gods forged Creation they imbued everything with a spirit of its own, a soul so to speak. The trees, the bushes, serpents and birds, everything was imbued with a soul. Even the very earth and the mountains got spirits of their own, as did the winds, the rain and the storms.
Angels are the guardians of Order, the forces that oversee that the purpose of existence is indeed fulfilled.
Demons are the darker emotions, the destructive forces of creation. In primeval times the demons awoke alongside the gods and the angels, and were herded by the greater powers, chased into hell, even as the angels were led into heaven.
Arakis's zombie problem went largely ignored, because it was believed that the Shai-Hulud (sand worms) would effectively dispose of the undead walkers. Unfortunately the problem grew until the roving herds of sunburnt ghouls threatened the flow of spice. While observing one of the great reanimated masses over take a Harvester from the safety of an ornithopter, an Imperial Zoologists noted that the sand caked flesh eating revenants walked entirely without rhythm.
Shortly after receiving this report the Bene Gesserits claimed to have a solution to Arakis's hellish resurrections. They asserted to the agents of the great houses that the worms could be drawn to the walkers using an ancient sonic weapon. According to the sisters, exposing the zombies to an antediluvian ballad composed by the great master M. Jackson would force them to step in time.