That was a speech in Vegas in 2011, let me explain that he was a private citizen in 2011, not running for president. Do you have a video of him saying the actual F word since august? Please post the URL...
The question was whether he was Christian or not. Did he become a Christian between 2011 and now? But that said, is early this year a good-enough reference?
He got a 2-fer on this one: the f word AND the s word.