Interestingly enough, I am of the mindset that any religion which is destroyed cannot have been a religion to a real god. Any god who allows a religion to be created to worship that god would not allow it to be destroyed - it would only make people think that god was not real.
This assumes that the god even cares in the first place. He could make a universe as a "side project" over a lunch break, flush the toilet, and go back to work. If the beings in that fleeting universe want to worship him as Creator, hey, whatever. Good job little creatures, you're absolutely right about me being a superior being that created you, and I couldn't possibly feel any less indifference toward you. Bye.
it would only make people think that god was not real
Blind faith can lead people to believe
anything, even to the point of seeing compassion and benevolence where there is truly nothing, not even indifference.
While this does not prove any of the current religions are true, it does provide us a way of showing some of the ones which are not true.
Or, it simply shows which organizations have developed the best staying power, which ones have the best marketing strategy. That which is alive may not necessarily be the best, or correct, solution. It just means that they're still around, at this particular moment.
Triceratops was around for awhile, but that lineage eventually died out completely.
But the crocodilian order has been around for much
much longer than humans, or primates. Does that mean they're a better solution to the problem of remaining alive on Earth? Not really. It just means that they're quite good at surviving. Primates will need quite a few more million years to prove ourselves out as a "better" survival. (And this of course is only a measure of how good a type of life form is at reproducing itself and surviving, which is not necessarily a measure of quality, which is also a very subjective concept.)
But it is still reliant on the assumption that a god entity would care about his created universe, or care about the thoughts and behaviors of the tiny flickering life forms within that universe.