Your generalization is not correct in this case. Mormonism historically has claimed that the bom is a testiment of a HISTORICAL visit of Jesus to the Americas and that the bom is a history of Jewish people in the Americas. That 'history' is testible, and to date that 'history' has been categorically rejected by science in multiple categories - archaeology, linguistics, dna, and anthropology to name a few key ones. While not EVERY location or even listed in the bible has been documented by archaeology or other means - scientists in the above categories overwhelminly note that the bible has a substantial degree of accuracy, for example cities and cultures mentioned in the bible are also mentioned in writings of other cultures of the same time period as well as those cultures and cites have been found. How does the bom stand up to similar test? Not a single artifact (city, writing, anything) has been discovered in the americas as authentic evidence of a race of hebraic peoples in the americas during the bom era - PERIOD.
Now pause and think about this - if the bom claims that the history recorded therein is FACTUAL - yet the FACTS show it to be completely FICTION, then the validity of its SPIRITUAL and MORAL inspiration and source for faith are equally questionable - particularly when the parallel claim is that 'GOD' provided the translation to smith. When you study all the factors as I have, the conclusion is clear - the bom is a piece of fiction that is being passed off as the word of 'god'. Thus in this case, writings DO affect the validity of one's faith, particularly when that "faith" is based upon a lie.
I agree, from what I have read of Mormon teachings, they are full of holes, and even provable lies. An attack on Glenn Beck, Romney, or Mormonism in general, is an attack on the Right. It is fully funded by George Soros and the left wing attack machine. If they spent as much time perusing the doctrines of Islam, I can understand that. Attacking the Mormons is an attempt to destroy the coalition that is needed to take the Left down.