The rationale behind President Obama’s decision to flip-flop on gay marriage and come out in favor of the idea isn’t any mystery. Democratic strategists rightly believe that any issue – no matter how divisive — that diverts attention from a failing economy is good for the president’s re-election campaign. That is why most Republicans have reacted to the matter with an impatient desire to get people talking about discouraging employment and growth figures. But that doesn’t mean the GOP didn’t reap an important dividend from last week’s big story.

The mainstream media has lionized the president for his stand, and most Americans may be either pleased or at least unopposed to gay marriage. But by choosing to embark on this initiative, President Obama has done his opponent in the November election a big favor. One of Mitt Romney’s biggest problems was the clear lack of enthusiasm for his candidacy on the part of his party’s base. But the endorsement of gay marriage is exactly what the Republican standard bearer needed to mobilize an army of evangelicals who were looking for a reason to get excited about an election in which they weren’t very happy about their choices. As the warm reception that Romney got at Liberty University this past weekend shows, he needn’t worry about his centrist image depressing the turnout figures among this key sector of Republican voters.

Throughout the campaign, the conventional wisdom has been that like 2008 GOP nominee John McCain, Romney would have trouble getting conservatives to care enough about his candidacy to work hard for his election. Moreover, even after he wrapped up the nomination, the fear has been that he would be caught between the twin perils of having to either continue to pander to evangelicals in the general election or losing them by shifting back to the center for the general election.

But Obama solved that problem for Romney with a single stroke that reminded Christian conservatives why they have no alternative but to turn out in November. When weighed against this blow to their values, factors such as Romney’s history of changed positions on abortion, his lack of fluency with the idiom of social conservative rhetoric and the unfortunate hesitancy on the part of some evangelicals to back a Mormon count for nothing.

After the administration’s assault on the Catholic Church in which the president’s signature health care program was used to force it to pay for practices it preaches against, there is a heightened awareness that religious freedom is going to be an issue in the election. And though, as the New York Times reports, the president has sought in the days after his decision to allay the fears of many pastors that his gay marriage stand will lead to government punishment of those faiths that don’t go along with his view, there is little doubt this is an unstated threat that scares many religious Americans. The example of Catholic and Orthodox Jewish institutions being run out of the adoption field in some states because of their views on gays is instructive.

President Obama needn’t fear African-American disaffection because of this issue even though many share the social conservative views of their white evangelical counterparts. In spite of their differences with this president on this point, black churches will continue to be rallying points for the president’s re-election.

But by pinning hopes on a belief that pushing liberal stands on social issues is the key to re-election, Obama has relieved Romney of the burden of having to spend any of the next six months worrying about whether evangelicals will turn out for him.