Polling religion

At The Talent Show, there's a post about how the majority of Americans polled are not only religious, but they seem to subscribe to old-fashioned, mythological, superstitious-type religion. check out the table.
Still, I wouldn't make too much of this. People lie to pollsters, and often. They tend to represent themeselves to pollsters as what they are expected to be more than what they really are. (I remember Katha Pollitt talking about catching herself lying to a pollster and claiming that she exercised everyday when the truth was the opposite.) With a subject as sensitive as religion, I would expect even more conformist-type answers than usual.
This doesn't tell you how many people believe in God and angels and the devil and whatnot. This mostly just tells you how many people are living under the pressure to say that they believe these things, and that's probably all. Of course, even that is worrisome. Why is it that 70% of Americans think that the socially appropriate belief is belief in the devil?