At least according to that paragon of investigative journalism Bill O'Reilly.
Read the article.
There are a couple of things we need to talk about here. First, the poll in question is about self identification. Americans' calling themselves Christian went down between '07 and'14 by about 8%, roughly the same amount of increase (given a margin of error) seen in the "atheist, agnostic, or nothing in particular" category. My contention is that the numerical change has nothing to do with practicing Christians, only those who were culturally Christian and no longer see a need to identify that way. I live in the heart of the South and I do not believe 70% of the people I encounter on a daily basis are Christians, no matter what they might say. I wish that we would get to the point where those who practice a faith regularly identify with that faith and no one else. In the long run it will make for stronger Christianity (and Islam, and Judaism, etc.) when the message is not watered down by the static generated by those who adopt a cultural stance without knowing or caring about the faith itself beyond habit.
Second, O'Rielly's claim is inherently xenophobic, a fear and distrust of anything that is unfamiliar or outside an individual's own culture which can include elements of racism, sexism, etc. He obvious fails to understand the genre he is criticizing, as the article points out. Pandering to fear is of the other sells. The Spanish-American war was the result of an effort to sell newspapers (remember, the Maine never happened).
Maybe O'Rilley would understand the point better from someone who looks a little more like him: Mr. B and his banjolele.
Then again, irony and sarcasm might be lost on Mr. O'Reilly.