That doesn't preclude that there may have been evangelicals in the battleground states which Romney needed who didn't vote.
Is there any evidence of an evangelical boycott in the battleground states where the election was lost?
There is a reduction of 3 million votes from the 2008 election. If the same people who had voted for John McCain had showed up, Romney would have won. We don't yet know exactly who these 3 million were that did not show up. They might be evangelicals, and so far I haven't heard a better explanation.
Do you have any better idea why we lost 3 million votes we had four years ago?
This thread might provide some useful information for you: