I’m no fan of Romney, but I don’t think he will slit his own throat by attacking evangelicals. He NEEDs them.
Romney himself will appear to stay above the fray, just like he did with Palin last election. It’s his surrogates who will attack Christian conservatives as religious bigots and/or Democrat operatives. It’s already happening, although I cannot prove it.
Romney does not need religious conservatives. He knows they will never vote for Obama, so he has no problem with their sitting on the sideline.
He’s going after the moderate vote, anyway, because the liberal vote constitutes only 20% of the electorate.