America was never really a christian nation. Most identified identify as Christians, but really had have no intention of actually following Christ. I am fine with a decline in church attendance.
Excellent point, Calvin (I 'updated' it for you!).
I refer to those people as 'practical atheists'. People who say they believe in God (and even Jesus as God), but whose lives are indistinguishable from other moral, non believers (including other religions). I have many friends that fall into this category. Their belief in God makes no appreciable difference in their lives vis-á-vis my unbelieving friends. Doesn't make them evil or bad people--just no different....
I believe other surveys have shown that ~80%+ Americans self-identify as 'christians'. Given the state of America (with regards to fundagelical standards), it would seem there are many 'practical atheists'.
Btw, the survey showed that it is not just church attendance declining but a significant reduction in 'believers'.