Three weeks ago, Mitt Romney was asked about the political impact of his religion, and he told Fox News, “I addressed this last time around…. That’s sort of been put to bed for me.” I wrote at the time that Romney’s Mormon faith was going “unnoticed.”

I guess that period is over.

The Values Voter Summit in Washington this weekend left no doubt about it: The Mormon issue is back.

A Texas pastor’s inflammatory remarks here — calling Mormonism a “cult” — thrust Mitt Romney’s faith into the center of a 2012 campaign overwhelmingly focused on the economy. It was a transparent attempt by Baptist minister Robert Jeffress, a Rick Perry supporter, to drive a wedge between Romney and evangelical voters.

The attack amounted to a test for Romney, forcing him to respond to a rhetorical assault on his faith that flouted the standard rules of American political debate.

For his part, Romney and his campaign had nothing to say about Jeffress, but the flap has given the media an excuse to start talking about an issue that has, up until now, been largely invisible. On the Sunday shows, for example, several Republican presidential candidates were asked whether they consider Mormonism a part of Christianity. Romney’s rivals didn’t want to talk about it.

It’s worth noting that, for now, the GOP field isn’t trying to use this issue as a wedge, at least not yet. Four years ago, Mike Huckabee took his campaign in an ugly direction, asking at one point, “Don’t Mormons believe that Jesus and the devil are brothers?” We’ve heard no similar rhetoric this year, at least not from the other candidates, and we can hope it stays that way.

And while it was probably inevitable that the campaign would spend at least some time on the “Mormon issue,” the larger question is whether voters actually care. A month ago, a New York Times/CBS News poll included a question related to the subject, without mentioning any candidates’ names: “Do you think most people you know would vote for a presidential candidate who is a Mormon, or not?” A 40% plurality said they believe people they know wouldn’t vote for a Mormon candidate.

Over the summer, Gallup asked voters — not just Republicans, but the public in general — whether they’d be willing to vote for a Mormon presidential candidate. The poll found 22% said they would not, a figure that’s up over the last few years.

I can think of all kinds of reasons Romney would made an awful president, but his religion is and should be irrelevant. If, however, bigotry is as common as the polls suggest, it’s an issue to keep an eye on.

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Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.