Any argument you could make, protestant vs. catholic (protestants being a satanic rejection of Catholicism, or Catholics themselves having fallen away from 'the true church' by virtue of Babylon's influence) can equally be made vs. Mormons and the LDS. You have to delve quite deep into the weeds to find a semblance of clarity.

Honestly, 'no true Scotsman' fallacies abound when you get into the differences between Christian sects (or try to find 'true' Christianity.) I think most dogma amounts to 'extra goofy beliefs tacked on,' and the essence of Christian spiritual practice is the same across sects. That said, the devil is in the details.