This interesting Newsweek profile of Mitt Romney gives a couple of great examples of exactly how hesitant he is to discuss his Mormon background in an honest way:
Nothing is more politically vexing or personally crucial for Republican presidential candidate Mitt Romney than the story of his faith. Raised in a devout Mormon family by parents who were both principled and powerful, Romney has downplayed both his religion and his own family history. Instead, he has talked up his résumé as a private-sector "turnaround artist" who reversed the fortunes of troubled companies and the faltering Salt Lake City Olympics and now can come to his party's—and country's—rescue. Mindful of the sway of evangelical Christians over the GOP base, he has positioned himself as the candidate with conservative principles and strong faith, even adopting evangelical language in calling Jesus Christ his "personal savior" (vernacular not generally used by members of the Mormon Church). But when he's pressed on the particulars of his own religious practice, his answers grow terse and he is quick to repeat that his values are rooted in "the Judeo-Christian tradition." [. . .]
Romney's biography is fully Mormon. When asked by NEWSWEEK if he has done baptisms for the dead—in which Mormons find the names of dead people of all faiths and baptize them, as an LDS spokesperson says, to "open the door" to the highest heaven—he looked slightly startled and answered, "I have in my life, but I haven't recently."
I'm not sure this is really such a sound approach. I always felt that Joe Lieberman (despite whatever else one might say about him) made a good run at being the first non-Christian on a national ticket precisely because he was so very clearly a practicing Orthodox Jew that it cleared the air. Romney, by acting weird and secretive, seems to be re-enforcing the idea that his faith is weird.