Outside of the sliver of people that research religion that remain religious, I absolutely know many religious people who have no concept of the relationship between other religions and how they would have the same deity involved. From my experience this would be most people, I don't know what your experience is nor do I have a quantitive study on this. I have talked to many people that would find this entire conversation alien and also offensive, just from their own lack of exposure. Even the idea of verifying this or merely opening the holy books to see that many of the chapters and stories are the same would be sacrilegious to them.