I’m right, therefore you must be wrong.

To be fair, Mormons are not the only ones who say this (though they are very pedantic about it).
A Jewish acquaintance of mine told me, in all seriousness, that the reason "gentile" prayers are not answered is because everyone else does not know how to pray. Non Jews in effect are mashing their fat palms in to the key pad of the telephone and hoping for the best, where as Jews have both a telephone book and a state of the art dialing wand allowing them a direct line to the Lord