I am convinced that most rank-and-file right-wing Christians are sincere and not cynical in the politics they embrace. Yet they have been so egregiously misled that even though they might be sincere, they are sincerely wrong according to the most fundamental moral and ethical imperatives of the Bible.
In culture war clashes, the word "sin" gets flung around loosely -- many Christians claim to "call a sin a sin," "take a stand against sin," and not "enable or aid sin." If I were to simply observe the issues on which Christians "take a stand," I'd conclude that the entire doctrine of sin is concerned primarily with sexual activity.
Sen. Mark Pryor's ad is a cautionary tale about the fact that, as he himself has said, the intersection of faith and politics can be difficult to navigate. It can come across as saying, "vote for me because I'm a Christian," a message that fails to respect America's constitutional ideals and growing religious pluralism.