To me, to suggest that someone is not saved because of their disbelief, different belief, or condemned to hell for same reason, is unwise, ineffective and insulting. Equally ineffective, hurtful and insulting is to tell call someone's god The Flying Spaghetti Monster or to tell the person he or she is delusional and listening to voices in their heads that don't exist.
FHN, I suspect there's something you may be confused about, since some atheists refer to THEIR God as the "Flying Spaghetti Monster"; it wouldn't be insulting to an atheist who believes in FSM for a believer to tell them their God IS FSM: they already know that, and it would be true.
But remember: FSM is NOT Jehovah, Allah, Ahuru Mazda, etc, but the made-up God of those atheists who accept FSM as their made-up God, offering salvation of free pasta for all (meatballs are given, based on the believer's works).
So no one was calling YOUR God (presumably Jehovah, the God of the Bible) the FSM: that would be heretical and insulting to an atheist, just like calling Jehovah The FSM would be insulting to a Xian. No one did that.
(And besides, FSM can wrap his noodly appendages around Jehovah's neck to strangle him, even with one noodle tied behind his meatball.)