With the advent of the internet, they are being challenged about the claim more and more.
You can see them label non-mormons "Mainstream Christians" on FR, thus being able to retain their identity as "special" (having the one "true" gospel) and still claim to be members of the greater Christian community.
“.....having the one “true” gospel”
Right. So this begs the question: If it’s the one true gospel why does it need the Bible to back it up? They’re always posting same passages (BOM vs Bible) - to prove a point.