I would be the last to deny that there are real and important theological differences between Mormonism and Protestantism or Catholicism. However, it is not simply these theological differences that account for the strange political salience of Mormonism as an issue for some non-trivial segment of the Republican base. Rather, I think that the fact that the details of Mormon theology matter so intensely as a political issue for some voters comes from their need to assert -- if only to themselves -- their theological integrity in the face of political compromises. It is not Mormon theology but the strange series of historical accidents that pushed conservative evangelical protestants and conservative catholics into alliance that is causing most of Romney's "Mormon problem," a development that Mormonism had very little to do with. Furthermore, the fact that this same non-trivial chunk of the Republican base believes that the theological marker for ecumenism is also a valid reason in principle for rejecting a Mormon candidate is simply a graphic illustration of the problems of conflating ecumenism and political coalition building. It also illustrates that at least for some, Mormonism's status as a religious outsider is sufficient reason to relegate Mormons to the status of outsiders within the political community as well. Supporter of a basically liberal political order (and member of the Mormon tribe) that I am, I find that a bit disquieting.
Point taken. I've spent a perhaps-inordinate amount of time defending the idea that it's reasonable to vote against a candidate because of his religious beliefs, and with that in mind I think it’s perfectly understandable that evangelical Christians would feel more comfortable voting for Huckabee than for Romney because they share a theological bedrock with the one and not the other. (In this vein, I like Matt's comments about how he wouldn't vote for a Jew for Jesus if there were other candidates on offer.) But these sort of choices, however understandable on an individual level, are problematic when they start defining a political coalition: The more religious conservatives appear to be treating theological issues, rather than the political issues they inform, as crucial election-season litmus tests, the more they’ll shrink their tent (there are a lot more Mormons than Jews for Jesus in the United States), alienate potential friends, and provide ammunition to the theocracy-shouters. If social conservatism is going to matter in American politics over the long run, then evangelicals would probably do well not to disqualify a Mormon from high office in advance, even if they choose not to vote for him when other alternatives are available. I’m not brave enough to venture into amateur speechwriting, but in an ideal world this is a point that Mitt Romney would strive – subtly, subtly – to get across on Thursday night.