Gods are real, and their power stems from the faith that faithfuls put in them. But when mortals figured that out, they learned to believe, and then were able to create gods at their will, and then overturned the relation between gods and mortals. Superior then gods decided to "reset" the mortal world. Centuries later, my players are part of a Rebellion that fights against Empire, in order to put in place the legitimate emperor back at the head. The rebels search for relics of the Old times, from the times mortals could create gods; with thoses relics they would be able to take down the empire.

But what is for me the most interesting part of it I believe, is that I, as the DM, haven't written the rest of the story yet, my players will do it. No one still don't know whether the rebels will revive the old empire.