That sentence is impossible for anyone on that island to say—if they worship Satan they can’t say it because it would be true, and if they worship God they can’t say it because it would be false. On the other hand, both can (and would) say they worship God.
“V jbefuvc fngna naq V’z zneevrq.” ?
That sentence is impossible for anyone on that island to say—if they worship Satan they can’t say it because it would be true, and if they worship God they can’t say it because it would be false. On the other hand, both can (and would) say they worship God.
A single satanist could say it.
Oh, right, if you treat it as one statement then it’s possible. But then it fails the modified question because you discover who they worship.