http://en.wikipedia.org/wiki/Crank_%28person%29
"Crank" is a pejorative term used for a person who unshakably holds a belief that most of his or her contemporaries consider to be false.[1] A "cranky" belief is so wildly at variance with commonly accepted belief as to be ludicrous. Cranks characteristically dismiss all evidence or arguments which contradict their own unconventional beliefs, making rational debate an often futile task.
Common synonyms for "crank" include crackpot and kook. A crank differs from a fanatic in that the subject of the fanatic's obsession is either not necessarily widely regarded as wrong or not necessarily a "fringe" belief. Similarly, the word quack is reserved for someone who promotes a medical remedy or practice that is widely considered to be ineffective; this term however does not imply any deep belief in the idea or product they are attempting to sell. Crank may also refer to an ill-tempered individual or one who is in a bad mood, but that usage is not the subject of this article.
Although a crank's beliefs seem ridiculous to experts in the field, cranks are sometimes very successful in convincing non-experts of their views. A famous example is the Indiana Pi Bill where a state legislature nearly wrote into law a crank result in geometry.
There is really no disputing this. You can't be a Mormon apologist (especially a professional apologist such as those published by the Maxwell Institute) and not also be a crank.