I feel a lot of people are making assumptions on how the Edicts/Anathemas system is going to work. I'm thinking it will be something along the lines of during character creation you can add any Edicts/Anathemas you wish, including none at all. These can help a GM understand your character's motivations easily or help you flesh out your character. All completely optional. To help facilitate this, Ancestries list some common Edicts/Anathemas for said Ancestry. These are intentionally vague so that they can apply broadly to the Ancestry. You could add "hunt the enemies of your people" exactly as written to your character's Edicts/Anathemas or use that as a jumping off point and add "hunt the necromantic cult that stole your ancestor's remains" because that fits your character.
Then, should you select a class such as cleric you add the deity's Edicts/Anathemas to your list. Should you violate those specific Anathemas you lose powers.
After character creation I see no reason the Edicts/Anathemas list couldn't have new ones added or existing ones removed as your character grows. Although Edicts/Anathemas added by class couldn't be dropped unless the source also dropped them.
tldr; I think the Edicts/Anathemas system will be more like a personal list of roleplaying guidelines and some classes add them and only those added have to be followed or you lose powers.