So can  someone be brought back from oblivion?

Something that is mentioned somewhat in passing in Priestess is the idea that if a deity loses their worshippers, they will lose their power and fade into oblivion.
This begs the question of whether a lost god or goddess can be brought back, even centuries later.  For a fantasy setting, I’m pretty much on board with the idea that a deity’s strength comes from how many worshippers they have.  If that’s the case, then at least in theory they should be reviveable, right?

Yes, I am already brainstorming my new story.  🙂

Let me know what you think about my theory as well as how you view fantasy gods and goddesses.  Supreme being?  Just more powerful?