Aaedra, commonly nicknamed Aether, is responsible for all good and is pure good with no signs of evil what so ever. Aether will only ever communicate with High Priests and offers a place in his kingdom of the Skylands to those who worship him and follow his set of rules.
There are eight types of worship to Aether. All believe that if they worship Aether they are reserved a place in the Skylands a heaven in which everything is pure good and is free of Daedra influence.
High Priests are a select few of Priests (temple owners) that Aether has selected to be communicated to. High Priests are told of things they must do or have fellow worshippers do in order to prevent Daedra influence over those who can be saved.
Daedra, nicknamed by few The Devil, is responsible for all bad and is nothing but evil. Daedra communicates with anyone he chooses and tempts them into committing evil deeds that please him. Daedra promises those he likes are reserved a safe place in the Abyss known as the Red Kingdoms where people can do as they please.
There are tons of ways to worship Daedra but the most common is Daedric Rituals in which you commit a set ritual every week, it can involve stealing, murder or nothing evil at all. They are heavily unpredictible.
There are five Daedric lords who are said to be pure evil, they only answer to Daedra and exist purely to spready Daedras evil. They are powerful beings who are worshipped by many as they believe the Daedric Lords only kill those who do not worship them. They are the only beings who can pass to and from the Abyss freely without a portal.
The Darkspawn are pure evil souls who are mindless and have no other instinct other than kill. They heavily populate the Abyss and can be summoned into the mortals plain by Daedric Magic, a powerful form of magic that only Daedra himself can perfect. Daedric Magic has killed 50 people who used all their power to cast a simple summoning spell that Daedra could do in his sleep. Its the most powerful yet evil and unpredictble magic known to man.