Agreed, but really this is no different than the Protestant and Catholics, or for that matter any number of schisms among the Protestants in the past few hundreds of years. Everyone who leaves is viewed as a heretic (apostate) and they will burn in hell forever for being so evil as to stand against God's chosen one >fill in the blank<.
Or for that matter it's no different than how Muslims, Jews, Hindus and Christians view each other. It's pretty much the same thing, isn't it?
Just because someone says God hates me simply because I don't go to their particular religious franchise, doesn't make it so. Now if or when a burning bush appears to me, or the heavens part and a giant finger points at me followed by a booming voice, okay then I'll listen. But until then . . .