Another if, fantasy, will never ever happen scenario. Ok, I'd let things exactly the way they are. In fact, the scenario doesn't make sense. First, today we do have the capacity of forming our own religion, second that fantasy scenario seems based on the premise that no other religion or way of thinking actually exist.
Anyway, since this is a never existed and never will scenario, I'd say I'd let thinks exactly the way they are since people are free to choose to believe whatever they choose, and because of the fact that anyone can come up with their own religion from scratch anyway.