The unreported tragedy of the missing former atheists - fortunately now found

One thing I have noticed in debating theists, particularly christians, is how often one will tell you they are a "former atheist".

If even half the Christians who paint themselves as "former atheists" had ever actually been recorded as such, atheism, instead of being the fastest growing (in raw numbers) "denomination" in the US, would be by far the fastest shrinking.

At a rough guess, I would say enough christians claim to be former atheists than would overwhelm the number of atheists in the 2008 ARIS survey by a factor of well over five. In the 2001 ARIS survey, the proportion of atheists was - get this - 0.4%; 4 in a thousand. Yet easily several percent of christians seem to proclaim "former atheism"?

What gives? Were they closet atheists?

Even stranger, this group of "former atheists" presents their "former atheism" in a light I have NEVER heard from actual atheists. They were, apparently, every kind of terrible thing that the less enlightened of the rabid rightwing fundies try to paint us as... and they are conveniently held up as experts on everything from science (especially evolution) to atheism to separation of church and state.

Now there are actually a few former atheists of now various theistic stripes whose former atheism was apparent to more than their later selves - so the phenomenon does occur.

But what about all these other ones that appear in debates, on message boards, on interviews, on youtube videos, as subjects of sermons, etc etc?

So where was this enormous group of thieving, drug-addicted, sexually deviant, but all-of-a-sudden-completely open to the message of christianity experts-on-every-subject hiding?

Why weren't they showing up in religious surveys?

Were they all hiding in one large (and presumably unbearably hip) basement?

Or, as seems much more likely, are they largely exaggerators-for-Jesus?