Authority

Information
Less faith means weaker Authority, and weak Authority can get stolen or disappear, which means an end to godhood. It’s not too hard to kill gods like that.

As for stealing Authority, well. Think about it like giving a subordinate of yours some power, but then they end up more popular than you, and before you know it they’re the boss. It’s kind of like that. You’ll be fine as long as that subordinate keeps worshiping you, though.