I’ve been a vocal critic of people (e.g. Fr. Richard John Neuhaus) who try to make Mitt Romney’s Mormonism a political issue against him.
Yes, in doctrinal terms Mormonism differs more from Catholicism, Protestantism, and Orthodoxy than those traditions differ from one another, to the point that an outsider classifying the world’s religions would have to think hard about whether to classify Mormonism as “Christian.” But no, that’s not a legitimate reason to vote against Romney.
To the extent that the specifically American political tradition is defined by the Constitution, which explicitly bars any religious test for office, using a candidate’s religion against him is un-American (though it can’t properly be said to be un-Constitutional, since the Constitution bars a statutory “test” but doesn’t dictate the behavior of voters or of campaigns).
Still, I have to agree with Atrios: Having said that “we need to have a person of faith lead the country” — in effect, proposing a voter-operated religious test that would bar atheists, agnostics, and skeptics — Romney has no kick coming when someone else wants to bar Mormons.
And Romney gets extra points off for having his spokesgeek denounce “other camps” for raising the issue when the fliers in question seem to have come from a random bunch of whackos.