The following is from Eric's ex-Mormon mailing list. It was in response to a discussion dealing with how LDS perform mental gymnastics in order to retain faith in their religion.
It is obvious that Mormons respond to the Mormon church and its doctrines in different ways. As a True Believing Mormon, I was aware of Jack Mormons, (non-practicing), wishy-washy Mormons (practicing but unenthusiastic), devout Mormons, and fundamentalist extremists.
Devout Mormons are more likely to study church teachings, including writings of various prophets. After all, studying the words of the prophets was a constant admonition within the church. Once you begin studying the "words of the prophets" you begin discovering the oddball stuff, like God having sex with Mary to conceive Jesus, anti-black sentiments, the idea that Adam is God the Father, as well as the polygamy issues (the church's deceptions concerning its practice, and the polyandrous unions).
Now, once a devout Mormon stumbles upon Brigham Young's thunderous declarations concerning the conception of Jesus, that devout Mormon will usually accept the "Word of the Lord" and incorporate it into their belief system, which of course will "leak" out during talks, lessons, etc. On the other hand, the Lukewarm Mormons have probably NOT been studying the "words of the prophets" (unless they happen also to be eccentric intellectuals) in the first place, therefore they have not confronted the "oddball" teachings. If viewed from this perspective, yes, then one could well maintain that there are definitely different "churches" within the "church". I do believe that the healthiest Mormons are the ones who don't take it seriously at all, just practice it for cultural reasons, and, after meetings, just go ahead and live life as they would otherwise.
Once I really began studying church history and the teachings of the prophets, I realized why the church always admonishes the members to "stay away from the mysteries". If one seriously pursues and attempts to incorporate the teachings of the Prophets, there is risk from one of two things: 1-leaving the church or 2-adhering to the fundamentalist position within the church, maybe even joining a splinter fundamentalist group. Obviously, the "main" LDS church doesn't like either of those two alternatives. Maybe one day they'll have to wise up and forbid reading of the Journal of Discourses (or other words of the prior 'prophets') at all. The safest route would be to only allow members to read the scriptures (minus perhaps the Pearl of Great Price and portions of the Old Testament), the Ensign, and Church News.